System and method for uplink multiple input multiple output transmission

ABSTRACT

Methods and apparatuses are provided for uplink MIMO transmissions in a wireless communication system. In particular, an enhanced pilot reference may be provided for enabling increased data rates on a secondary stream. Specifically, a primary stream, provided on a primary virtual antenna, includes an enhanced primary data channel E-DPDCH, a primary control channel DPCCH, and an enhanced primary control channel E-DPCCH. Further, a secondary stream, provided on a secondary virtual antenna, includes an enhanced secondary data channel S-E-DPDCH and a secondary control channel S-DPCCH. Here, the secondary control channel S-DPCCH may be transmitted at a boosted power level relative to a determined reference power level.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of provisionalpatent application No. 61/411,454, filed in the United States Patent andTrademark office on Nov. 8, 2010, the entire content of which isincorporated herein by reference.

BACKGROUND

1. Field

Aspects of the present disclosure relate generally to wirelesscommunication systems, and more particularly, to power level boosting ofcontrol channels for uplink MIMO transmissions.

2. Background

Wireless communication networks are widely deployed to provide variouscommunication services such as telephony, video, data, messaging,broadcasts, and so on. Such networks, which are usually multiple accessnetworks, support communications for multiple users by sharing theavailable network resources. One example of such a network is the UMTSTerrestrial Radio Access Network (UTRAN). The UTRAN is the radio accessnetwork (RAN) defined as a part of the Universal MobileTelecommunications System (UMTS), a third generation (3G) mobile phonetechnology supported by the 3rd Generation Partnership Project (3GPP).The UMTS, which is the successor to Global System for MobileCommunications (GSM) technologies, currently supports various airinterface standards, such as Wideband-Code Division Multiple Access(W-CDMA), Time Division-Code Division Multiple Access (TD-CDMA), andTime Division-Synchronous Code Division Multiple Access (TD-SCDMA). TheUMTS also supports enhanced 3G data communications protocols, such asHigh Speed Packet Access (HSPA), which provides higher data transferspeeds and capacity to associated UMTS networks.

As the demand for mobile broadband access continues to increase,research and development continue to advance the UMTS technologies notonly to meet the growing demand for mobile broadband access, but toadvance and enhance the user experience with mobile communications.

For example, recent releases of 3GPP standards for UMTS technologieshave included multiple input multiple output (MIMO) for downlinktransmissions. MIMO can enable increased throughput in a transmissionwithout requiring a commensurate increase in spectrum use, since twostreams can be transmitted in the same carrier frequency, where they areseparated by the spatial dimension by being transmitted from spatiallyseparate antennas. In this way, an effective doubling of spectralefficiency can be achieved by transmitting dual transport blocks pertransmission time interval.

Further, recent attention within the 3GPP standards body has beendirected to a particular uplink beamforming transmit diversity (BFTD)scheme for high speed packet access (HSPA) networks within the UMTSstandards, where a mobile terminal utilizes two transmit antennas andtwo power amplifiers for uplink transmissions. This scheme, whenimplemented in a closed loop mode under network control, has shownsignificant improvement in cell edge user experience, as well as overallimprovements in system performance. However, in schemes that have beeninvestigated, the mobile terminal has been limited to single streamtransmissions across the two antennas.

Therefore, to increase the throughput and spectral efficiency for uplinktransmissions, there is a desire to implement MIMO for uplinktransmissions such that dual transport blocks can be transmitted in thesame carrier frequency during the same transmission time interval.

SUMMARY

Various aspects of the present disclosure provide for uplink MIMOtransmissions in a wireless communication system. In some particularaspects of the disclosure, an enhanced pilot reference may be providedfor enabling increased data rates on a secondary stream. Specifically, aprimary stream, provided on a primary virtual antenna, includes anenhanced primary data channel E-DPDCH, a primary control channel DPCCH,and an enhanced primary control channel E-DPCCH. Further, a secondarystream, provided on a secondary virtual antenna, includes an enhancedsecondary data channel S-E-DPDCH and a secondary control channelS-DPCCH. Here, the secondary control channel S-DPCCH may be transmittedat a boosted power level relative to a determined reference power level.

For example, in one aspect, the disclosure provides a method of wirelesscommunication that includes transmitting a primary control channel andan enhanced primary data channel on a first virtual antenna, determininga reference power level corresponding to a secondary control channel,transmitting an enhanced secondary data channel on a second virtualantenna, and transmitting the secondary control channel on the secondvirtual antenna at a boosted power level relative to the reference powerlevel.

In another aspect, the disclosure provides a base station configured forwireless communication. Here, the base station includes means fortransmitting a primary control channel and an enhanced primary datachannel on a first virtual antenna, means for determining a referencepower level corresponding to a secondary control channel, means fortransmitting an enhanced secondary data channel on a second virtualantenna, and means for transmitting the secondary control channel on thesecond virtual antenna at a boosted power level relative to thereference power level.

In yet another aspect, the disclosure provides a computer programproduct, which includes a computer-readable medium having instructionsfor causing a computer to transmit a primary control channel and anenhanced primary data channel on a first virtual antenna, to determine areference power level corresponding to a secondary control channel, totransmit an enhanced secondary data channel on a second virtual antenna,and to transmit the secondary control channel on the second virtualantenna at a boosted power level relative to the reference power level.

In still another aspect, the disclosure provides an apparatus forwireless communication, which includes a transmitter for transmitting aprimary virtual antenna and a secondary virtual antenna, at least oneprocessor for controlling the transmitter, and a memory coupled to theat least one processor. Here, the at least one processor is configuredto transmit a primary control channel and an enhanced primary datachannel on the primary virtual antenna, to determine a reference powerlevel corresponding to a secondary control channel, to transmit anenhanced secondary data channel on the secondary virtual antenna, and totransmit the secondary control channel on the secondary virtual antennaat a boosted power level relative to the reference power level.

These and other aspects of the invention will become more fullyunderstood upon a review of the detailed description, which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual diagram illustrating an example of an accessnetwork.

FIG. 2 is a block diagram conceptually illustrating an example of atelecommunications system.

FIG. 3 is a conceptual diagram illustrating an example of a radioprotocol architecture for the user and control plane.

FIG. 4 is a block diagram illustrating a portion of a MAC layerimplementing dual HARQ processes.

FIG. 5 is a block diagram illustrating additional portions of the MAClayer illustrated in FIG. 4.

FIG. 6 is a block diagram illustrating a portion of a transmitterconfigured for uplink MIMO transmissions.

FIG. 7 is a graph showing relative power levels of certain physicalchannels in uplink MIMO transmissions.

FIG. 8 is a flow chart illustrating a process for setting power levelsand transport block sizes in accordance with a scheduling grant.

FIG. 9 is a flow chart illustrating a process for generating datainformation and its associated control information and providing thisinformation on respective physical channels.

FIG. 10 is a flow chart illustrating a process for boosting a power of asecondary pilot channel.

FIG. 11 is a flow chart illustrating a process operable at a networknode for inner loop power control of uplink MIMO transmissions.

FIG. 12 is a flow chart illustrating a process operable at a userequipment for inner loop power control of uplink MIMO transmissions.

FIG. 13 is a flow chart illustrating another process operable at a userequipment for inner loop power control of uplink MIMO transmissions.

FIG. 14 is a flow chart illustrating a process operable at a networknode for outer loop power control of uplink MIMO transmissions.

FIG. 15 is a flow chart illustrating a process operable at a userequipment for scheduling an uplink transmission in the presence of HARQretransmissions.

FIG. 16 is a flow chart illustrating another process operable at a userequipment for scheduling an uplink transmission in the presence of HARQretransmissions.

FIG. 17 is a flow chart illustrating another process operable at a userequipment for scheduling an uplink transmission in the presence of HARQretransmissions.

FIG. 18 is a flow chart illustrating another process operable at a userequipment for scheduling an uplink transmission in the presence of HARQretransmissions.

FIG. 19 is a flow chart illustrating another process operable at a userequipment for scheduling an uplink transmission in the presence of HARQretransmissions.

FIG. 20 is an example of a hardware implementation for an apparatusemploying a processing system.

FIG. 21 is a block diagram conceptually illustrating an example of aNode B in communication with a UE in a telecommunications system.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

The various concepts presented throughout this disclosure may beimplemented across a broad variety of telecommunication systems, networkarchitectures, and communication standards. Referring to FIG. 1, by wayof example and without limitation, a simplified access network 100 in aUMTS Terrestrial Radio Access Network (UTRAN) architecture, which mayutilize High-Speed Packet Access (HSPA), is illustrated. The systemincludes multiple cellular regions (cells), including cells 102, 104,and 106, each of which may include one or more sectors. Cells may bedefined geographically, e.g., by coverage area, and/or may be defined inaccordance with a frequency, scrambling code, etc. That is, theillustrated geographically-defined cells 102, 104, and 106 may each befurther divided into a plurality of cells, e.g., by utilizing differentfrequencies or scrambling codes. For example, cell 104 a may utilize afirst frequency or scrambling code, and cell 104 b, while in the samegeographic region and served by the same Node B 144, may bedistinguished by utilizing a second frequency or scrambling code.

In a cell that is divided into sectors, the multiple sectors within acell can be formed by groups of antennas with each antenna responsiblefor communication with UEs in a portion of the cell. For example, incell 102, antenna groups 112, 114, and 116 may each correspond to adifferent sector. In cell 104, antenna groups 118, 120, and 122 eachcorrespond to a different sector. In cell 106, antenna groups 124, 126,and 128 each correspond to a different sector.

The cells 102, 104 and 106 may include several UEs that may be incommunication with one or more sectors of each cell 102, 104 or 106. Forexample, UEs 130 and 132 may be in communication with Node B 142, UEs134 and 136 may be in communication with Node B 144, and UEs 138 and 140may be in communication with Node B 146. Here, each Node B 142, 144, 146is configured to provide an access point to a core network 204 (see FIG.2) for all the UEs 130, 132, 134, 136, 138, 140 in the respective cells102, 104, and 106.

Referring now to FIG. 2, by way of example and without limitation,various aspects of the present disclosure are illustrated with referenceto a Universal Mobile Telecommunications System (UMTS) system 200employing a wideband code division multiple access (W-CDMA) airinterface. A UMTS network includes three interacting domains: a CoreNetwork (CN) 204, a UMTS Terrestrial Radio Access Network (UTRAN) 202,and User Equipment (UE) 210. In this example, the UTRAN 202 may providevarious wireless services including telephony, video, data, messaging,broadcasts, and/or other services. The UTRAN 202 may include a pluralityof Radio Network Subsystems (RNSs) such as the illustrated RNSs 207,each controlled by a respective Radio Network Controller (RNC) such asan RNC 206. Here, the UTRAN 202 may include any number of RNCs 206 andRNSs 207 in addition to the illustrated RNCs 206 and RNSs 207. The RNC206 is an apparatus responsible for, among other things, assigning,reconfiguring and releasing radio resources within the RNS 207. The RNC206 may be interconnected to other RNCs (not shown) in the UTRAN 202through various types of interfaces such as a direct physicalconnection, a virtual network, or the like, using any suitable transportnetwork.

The geographic region covered by the RNS 207 may be divided into anumber of cells, with a radio transceiver apparatus serving each cell. Aradio transceiver apparatus is commonly referred to as a Node B in UMTSapplications, but may also be referred to by those skilled in the art asa base station (BS), a base transceiver station (BTS), a radio basestation, a radio transceiver, a transceiver function, a basic serviceset (BSS), an extended service set (ESS), an access point (AP), or someother suitable terminology. For clarity, three Node Bs 208 are shown ineach RNS 207; however, the RNSs 207 may include any number of wirelessNode Bs. The Node Bs 208 provide wireless access points to a corenetwork (CN) 204 for any number of mobile apparatuses. Examples of amobile apparatus include a cellular phone, a smart phone, a sessioninitiation protocol (SIP) phone, a laptop, a notebook, a netbook, asmartbook, a personal digital assistant (PDA), a satellite radio, aglobal positioning system (GPS) device, a multimedia device, a videodevice, a digital audio player (e.g., MP3 player), a camera, a gameconsole, or any other similar functioning device. The mobile apparatusis commonly referred to as user equipment (UE) in UMTS applications, butmay also be referred to by those skilled in the art as a mobile station(MS), a subscriber station, a mobile unit, a subscriber unit, a wirelessunit, a remote unit, a mobile device, a wireless device, a wirelesscommunications device, a remote device, a mobile subscriber station, anaccess terminal (AT), a mobile terminal, a wireless terminal, a remoteterminal, a handset, a terminal, a user agent, a mobile client, aclient, or some other suitable terminology. In a UMTS system, the UE 210may further include a universal subscriber identity module (USIM) 211,which contains a user's subscription information to a network. Forillustrative purposes, one UE 210 is shown in communication with anumber of the Node Bs 208. The downlink (DL), also called the forwardlink, refers to the communication link from a Node B 208 to a UE 210,and the uplink (UL), also called the reverse link, refers to thecommunication link from a UE 210 to a Node B 208.

The core network 204 interfaces with one or more access networks, suchas the UTRAN 202. As shown, the core network 204 is a GSM core network.However, as those skilled in the art will recognize, the variousconcepts presented throughout this disclosure may be implemented in aRAN, or other suitable access network, to provide UEs with access totypes of core networks other than GSM networks.

The illustrated GSM core network 204 includes a circuit-switched (CS)domain and a packet-switched (PS) domain. Some of the circuit-switchedelements are a Mobile services Switching Centre (MSC), a VisitorLocation Register (VLR), and a Gateway MSC (GMSC). Packet-switchedelements include a Serving GPRS Support Node (SGSN) and a Gateway GPRSSupport Node (GGSN). Some network elements, like EIR, HLR, VLR and AuCmay be shared by both of the circuit-switched and packet-switcheddomains.

In the illustrated example, the core network 204 supportscircuit-switched services with a MSC 212 and a GMSC 214. In someapplications, the GMSC 214 may be referred to as a media gateway (MGW).One or more RNCs, such as the RNC 206, may be connected to the MSC 212.The MSC 212 is an apparatus that controls call setup, call routing, andUE mobility functions. The MSC 212 also includes a visitor locationregister (VLR) that contains subscriber-related information for theduration that a UE is in the coverage area of the MSC 212. The GMSC 214provides a gateway through the MSC 212 for the UE to access acircuit-switched network 216. The GMSC 214 includes a home locationregister (HLR) 215 containing subscriber data, such as the datareflecting the details of the services to which a particular user hassubscribed. The HLR is also associated with an authentication center(AuC) that contains subscriber-specific authentication data. When a callis received for a particular UE, the GMSC 214 queries the HLR 215 todetermine the UE's location and forwards the call to the particular MSCserving that location.

The illustrated core network 204 also supports packet-data services witha serving GPRS support node (SGSN) 218 and a gateway GPRS support node(GGSN) 220. GPRS, which stands for General Packet Radio Service, isdesigned to provide packet-data services at speeds higher than thoseavailable with standard circuit-switched data services. The GGSN 220provides a connection for the UTRAN 202 to a packet-based network 222.The packet-based network 222 may be the Internet, a private datanetwork, or some other suitable packet-based network. The primaryfunction of the GGSN 220 is to provide the UEs 210 with packet-basednetwork connectivity. Data packets may be transferred between the GGSN220 and the UEs 210 through the SGSN 218, which performs primarily thesame functions in the packet-based domain as the MSC 212 performs in thecircuit-switched domain.

The UMTS air interface may be a spread spectrum Direct-Sequence CodeDivision Multiple Access (DS-CDMA) system. The spread spectrum DS-CDMAspreads user data through multiplication by a sequence of pseudorandombits called chips. The W-CDMA air interface for UMTS is based on suchDS-CDMA technology and additionally calls for a frequency divisionduplexing (FDD). FDD uses a different carrier frequency for the uplink(UL) and downlink (DL) between a Node B 208 and a UE 210. Another airinterface for UMTS that utilizes DS-CDMA, and uses time divisionduplexing (TDD), is the TD-SCDMA air interface. Those skilled in the artwill recognize that although various examples described herein may referto a W-CDMA air interface, the underlying principles are equallyapplicable to a TD-SCDMA air interface.

A high speed packet access (HSPA) air interface includes a series ofenhancements to the 3G/W-CDMA air interface, facilitating greaterthroughput and reduced latency. Among other modifications over priorreleases, HSPA utilizes hybrid automatic repeat request (HARM), sharedchannel transmission, and adaptive modulation and coding. The standardsthat define HSPA include HSDPA (high speed downlink packet access) andHSUPA (high speed uplink packet access, also referred to as enhanceduplink, or EUL).

In a wireless telecommunication system, the radio protocol architecturebetween a mobile device and a cellular network may take on various formsdepending on the particular application. An example for a 3GPPhigh-speed packet access (HSPA) system will now be presented withreference to FIG. 3, illustrating an example of the radio protocolarchitecture for the user and control planes between the UE 210 and theNode B 208. Here, the user plane or data plane carries user traffic,while the control plane carries control information, i.e., signaling.

Turning to FIG. 3, the radio protocol architecture for the UE 210 andNode B 208 is shown with three layers: Layer 1, Layer 2, and Layer 3.Although not shown, the UE 210 may have several upper layers above theL3 layer including a network layer (e.g., IP layer) that is terminatedat a PDN gateway on the network side, and an application layer that isterminated at the other end of the connection (e.g., far end UE, server,etc.).

At Layer 3, the RRC layer 316 handles control plane signaling betweenthe UE 210 and the Node B 208. RRC layer 316 includes a number offunctional entities for routing higher layer messages, handlingbroadcast and paging functions, establishing and configuring radiobearers, etc.

The data link layer, called Layer 2 (L2 layer) 308 is between Layer 3and the physical layer 306, and is responsible for the link between theUE 210 and Node B 208. In the illustrated air interface, the L2 layer308 is split into sublayers. In the control plane, the L2 layer 308includes two sublayers: a medium access control (MAC) sublayer 310 and aradio link control (RLC) sublayer 312. In the user plane, the L2 layer308 additionally includes a packet data convergence protocol (PDCP)sublayer 314. Of course, those of ordinary skill in the art willcomprehend that additional or different sublayers may be utilized in aparticular implementation of the L2 layer 308, still within the scope ofthe present disclosure.

The PDCP sublayer 314 provides multiplexing between different radiobearers and logical channels. The PDCP sublayer 314 also provides headercompression for upper layer data packets to reduce radio transmissionoverhead, security by ciphering the data packets, and handover supportfor UEs between Node Bs.

The RLC sublayer 312 provides segmentation and reassembly of upper layerdata packets, retransmission of lost data packets, and reordering ofdata packets to compensate for out-of-order reception due to a hybridautomatic repeat request (HARM).

The MAC sublayer 310 provides multiplexing between logical channels andtransport channels. The MAC sublayer 310 is also responsible forallocating the various radio resources (e.g., resource blocks) in onecell among the UEs. The MAC sublayer 310 is also responsible for HARQoperations.

Layer 1 is the lowest layer and implements various physical layer signalprocessing functions. Layer 1 will be referred to herein as the physicallayer (PHY) 306. At the PHY layer 306, the transport channels are mappedto different physical channels.

Data generated at higher layers, all the way down to the MAC layer 310,are carried over the air through transport channels. 3GPP Release 5specifications introduced downlink enhancements referred to as HSDPA.HSDPA utilizes as its transport channel the high-speed downlink sharedchannel (HS-DSCH). The HS-DSCH is implemented by three physicalchannels: the high-speed physical downlink shared channel (HS-PDSCH),the high-speed shared control channel (HS-SCCH), and the high-speeddedicated physical control channel (HS-DPCCH).

Among these physical channels, the HS-DPCCH carries HARQ ACK/NACKsignaling on the uplink to indicate whether a corresponding packettransmission was decoded successfully. That is, with respect to thedownlink, the UE 210 provides feedback to the Node B 208 over theHS-DPCCH to indicate whether it correctly decoded a packet on thedownlink.

HS-DPCCH further includes feedback signaling from the UE 210 to assistthe Node B 208 in taking the right decision in terms of modulation andcoding scheme and precoding weight selection, this feedback signalingincluding the channel quality indicator (CQI) and precoding controlinformation (PCI).

3GPP Release 6 specifications introduced uplink enhancements referred toas Enhanced Uplink (EUL) or High Speed Uplink Packet Access (HSUPA).HSUPA utilizes as its transport channel the EUL Dedicated Channel(E-DCH). The E-DCH is transmitted in the uplink together with theRelease 99 DCH. The control portion of the DCH, that is, the DPCCH,carries pilot bits and downlink power control commands on uplinktransmissions. In the present disclosure, the DPCCH may be referred toas a control channel (e.g., a primary control channel) or a pilotchannel (e.g., a primary pilot channel) in accordance with whetherreference is being made to the channel's control aspects or its pilotaspects.

The E-DCH is implemented by physical channels including the E-DCHDedicated Physical Data Channel (E-DPDCH) and the E-DCH DedicatedPhysical Control Channel (E-DPCCH). In addition, HSUPA relies onadditional physical channels including the E-DCH HARQ Indicator Channel(E-HICH), the E-DCH Absolute Grant Channel (E-AGCH), and the E-DCHRelative Grant Channel (E-RGCH). Further, in accordance with aspects ofthe present disclosure, for HSUPA with MIMO utilizing two transmitantennas, the physical channels include a Secondary E-DPDCH (S-E-DPDCH),a Secondary E-DPCCH (S-E-DPCCH), and a Secondary DPCCH (S-DPCCH).Additional information about these channels is provided below.

That is, part of the ongoing development of HSPA standards (includingHSDPA and EUL) includes the addition of multiple-input, multiple-output(MIMO) communication. MIMO generally refers to the use of multipleantennas at the transmitter (multiple inputs to the channel) and thereceiver (multiple outputs from the channel) to implement spatialmultiplexing, that is, the transmission and/or reception of differentstreams of information from spatially separated antennas, utilizing thesame carrier frequency for each stream. Such a scheme can increasethroughput, that is, can achieve higher data rates without necessarilyexpanding the channel bandwidth, thus improving spectral efficiency.That is, in an aspect of the disclosure, the Node B 208 and/or the UE210 may have multiple antennas supporting MIMO technology.

MIMO for increased downlink performance was implemented in Release 7 ofthe 3GPP UMTS standards for HSDPA, and Release 9 included DC-HSDPA+MIMOfor further increased downlink performance. In HSDPA MIMO the Node B 208and the UE 210 each utilize two antennas, and a closed loop feedbackfrom the UE 210 (Precoding Control Information, PCI) is utilized todynamically adjust the Node B's transmit antenna weighting. When channelconditions are favorable, MIMO can allow a doubling of the data rate bytransmitting two data streams, utilizing spatial multiplexing. Whenchannel conditions are less favorable, a single stream transmission overthe two antennas can be utilized, providing some benefit from transmitdiversity.

While MIMO in the uplink would be desirable for essentially the samereasons it has been implemented for the downlink, it has been consideredsomewhat more challenging, in part because the battery power-constrainedUE may need to include two power amplifiers. Nonetheless, more recentlyan uplink beamforming transmit diversity (BFTD) scheme for HSPA thatutilizes 2 transmit antennas and 2 power amplifiers at the UE 210 hasgarnered substantial interest, and studies have been directed to bothopen loop and closed loop modes of operation. These studies have shownimprovements in cell edge user experience and overall systemperformance. However, these uplink transmit diversity schemes havegenerally been limited to single code word or single transport blocktransmissions utilizing dual transmit antennas.

Thus, various aspects of the present disclosure provide for uplink MIMOtransmissions. For clarity by providing explicit details, the presentdescription utilizes HSUPA terminology and generally assumes a 3GPPimplementation in accordance with UMTS standards. However, those ofordinary skill in the art will understand that many if not all thesefeatures are not specific to a particular standard or technology, andmay be implemented in any suitable technology for MIMO transmissions.

In an HSUPA system, data transmitted on a transport channel such as theE-DCH is generally organized into transport blocks. During eachtransmission time interval (TTI), without the benefits of spatialmultiplexing, at most one transport block of a certain size (thetransport block size or TBS) can be transmitted per carrier on theuplink from the UE 210. However, with MIMO using spatial multiplexing,multiple transport blocks can be transmitted per TTI in the samecarrier, where each transport block corresponds to one code word. In aconventional HSUPA transmission, or even in more recent advancementsrelating to uplink CLTD, both of which are configured for single streamrank=1 transmissions, both 2 ms and 10 ms TTIs may generally beconfigured, since the longer 10 ms TTI can provide improved performanceat the cell edge. However, in a UE 210 configured for dual streamtransmissions, a primary motivation may be to increase the data rate.Here, since the 10 ms TTI generally has a limited data rate compared tothat available with a 2 ms TTI, in accordance with some aspects of thepresent disclosure, to ensure an improvement in the data rate, rank=2transmissions might be limited to the utilization of the 2 ms TTI.

As illustrated in FIG. 4, in an aspect of the present disclosure, thetransmission of dual transport blocks on the two precoding vectors maybe implemented across dual HARQ processes during the same TTI. Here, thedual transport blocks are provided on one E-DCH transport channel. Ineach HARQ process, when a transport block on the E-DCH is received fromhigher layers, the process for mapping that transport block to thephysical channels E-DPDCH (or, when utilizing the secondary transportblock, the S-E-DPDCH) may include several operations such as CRCattachment 404, 454; code block segmentation 406, 456; channel coding408, 458; rate matching 410, 460; physical channel segmentation 412,462; and interleaving/physical channel mapping 414, 464. Details ofthese blocks are largely known to those of ordinary skill in the art,and are therefore omitted from the present disclosure. FIG. 4illustrates this process for the generation of an UL MIMO transmissionusing dual transport blocks 402, 452. This scheme is frequently referredto as a multiple code word scheme, since each of the transmitted streamsmay be precoded utilizing separate codewords. In some aspects of thedisclosure, the E-DCH processing structure is essentially identical foreach of the two transport blocks. Additionally, this scheme isfrequently referred to as a dual stream scheme, where the primarytransport bock is provided on the primary stream, and the secondarytransport block is provided on the secondary stream.

FIG. 5 provides another example in accordance with the presentdisclosure, including circuitry additional to that illustrated in FIG.4, showing operation of a Multiplexing and Transmission Sequence Number(TSN) setting entity 502, an E-DCH Transport Format Combination (E-TFC)selection entity 504, and a Hybrid Automatic Repeat Request (HARQ)entity 506 within a UE such as the UE 210.

Each of the E-TFC selection entity 504, the multiplexing and TSN settingentity 502, and the HARQ entity 506 may include a processing system 2014as illustrated in FIG. 20, described below, for performing processingfunctions such as making determinations relating to the E-DCH transportformat combination, handling MAC protocol data units, and performingHARQ functions, respectively. Of course, some or all of the respectiveentities may be combined into a single processor or processing system114. Here, the processing system 2014 may control aspects of thetransmission of the primary and secondary streams as described below.

In some aspects of the present disclosure, in accordance with receivedgrant information 508 on the E-AGCH and E-RGCH, and based in part on adetermination of which configuration results in better data throughput,the E-TFC selection entity 504 may determine either to transmit a singletransport or dual transport blocks, and may accordingly determine thetransport block size(s) and power levels to utilize on the stream orstreams. For example, the E-TFC selection entity 504 may determinewhether to transmit a single transport block (e.g., utilizing uplinkbeamforming transmit diversity), or dual transmit blocks (e.g.,utilizing spatial multiplexing). In this example, the multiplexing andTSN setting entity 502 may concatenate multiple MAC-d Protocol DataUnits (PDUs) or segments of MAC-d PDUs into MAC-is PDUs, and may furthermultiplex one or more MAC-is PDUs into a single MAC-i PDU to betransmitted in the following TTI, as instructed by the E-TFC selectionentity 504. The MAC-i PDU may correspond to the transport block providedon a corresponding stream. That is, in some aspects of the disclosure,if the E-TFC selection entity determines to transmit two transportblocks, then two MAC-i PDUs may be generated by the Multiplexing and TSNSetting entity 502 and delivered to the HARQ entity 506.

Scheduling Grants

In some aspects of the disclosure, a scheduler at the Node B 208 mayprovide scheduling information 508 to the UE 210 on a per-stream basis.The scheduling of a UE 210 may be made in accordance with variousmeasurements made by the Node B 208 such as the noise level at the NodeB receiver, with various feedback information transmitted on the uplinkby UEs such as a “happy bit,” buffer status, and transmission poweravailability, and with priorities or other control information providedby the network. That is, when MIMO is selected, the scheduler at theNode B 208 may generate and transmit two grants, e.g., one for eachstream during each TTI.

For example, the E-DCH Absolute Grant Channel (E-AGCH) is a physicalchannel that may be utilized to carry information from the Node B 208 tothe E-TFC selection entity 504 of the UE 210 for controlling the powerand transmission rate of uplink transmissions by the UE 210 on theE-DCH. In some examples, the E-AGCH can be a common channel that masksthe 16 CRC bits with the UE's primary E-RNTI.

In addition to the scheduling grant information provided on the E-AGCH,further scheduling grant information may also be conveyed from the NodeB 208 to the E-TFC selection entity 504 of the UE 210 over the E-DCHRelative Grant Channel (E-RGCH). Here, the E-RGCH may be utilized forsmall adjustments during ongoing data transmissions. In an aspect of thepresent disclosure, in uplink MIMO, the UE 210 may be allocated tworesources on the E-RGCH to carry relative scheduling grants for theprimary and secondary HARQ processes, e.g., corresponding to the primaryand secondary precoding vectors.

The grant provided on the E-AGCH can change over time for a particularUE, so grants may be periodically or intermittently transmitted by theNode B 208. The absolute grant value carried on the E-AGCH may indicatethe maximum E-DCH traffic to pilot power ratio (T/P) that the UE 210 isallowed to use in its next transmission.

In some examples, the Node B 208 may transmit two E-AGCH channels to theUE 210, wherein each E-AGCH is configured in the same way as Release-7E-AGCH. Here, the UE 210 may be configured to monitor both E-AGCHchannels each TTI. In another example in accordance with various aspectsof the present disclosure, a new type of E-AGCH physical channel may beutilized, wherein Release-7 E-AGCH channel coding is utilizedindependently to encode the absolute grant information bits for eachstream, and wherein the spreading factor is reduced by 2, i.e., toSF=128 to accommodate more bits of information. Here, joint encoding ofthe absolute grant information for both streams may utilize the primaryE-RNTI of the UE 210.

In yet another example in accordance with various aspects of the presentdisclosure, a new type of E-AGCH channel coding may be utilized, whereinthe absolute grant information bits are jointly encoded. Here, thelegacy Release-7 E-AGCH physical channel, with the spreading factorSF=256 may be utilized. This example may be the most attractive for boththe UE 210 as well as the Node B 208, considering UE implementation andNode B code resources.

Here, the absolute grant provided on the E-AGCH may be used by the UE210 in UL MIMO to determine (1) transport block sizes (TBS) for theprimary and secondary transport blocks to be transmitted in the nextuplink transmission; (2) the transmit power on the E-DPDCH(s) and on theS-E-DPDCH(s); and (3) the rank of the transmission. As described above,the TBS is the size of a block of information transmitted on a transportchannel (e.g., the E-DCH) during a TTI. The transmit “power” may beprovided to the UE 210 in units of dB, and may be interpreted by the UE210 as a relative power, e.g., relative to the power level of the DPCCH,referred to herein as a traffic to pilot power ratio. Further, if therank of the transmission is rank=1, then only the E-DPDCH(s) aretransmitted on a primary precoding vector. If the rank of thetransmission is rank=2, then both the E-DPDCHs and the S-E-DPDCHs aretransmitted, i.e., on the primary precoding vector and the secondaryprecoding vector, respectively.

For example, in an aspect of the present disclosure, the schedulingsignaling 508 may indicate that the rank of the transmission is rank=1corresponding to a single stream, by including in the E-AGCH a singlescheduling grant (T/P)_(SS). Here, the single-stream scheduling grant(T/P)_(SS) may be utilized by the E-TFC selection entity 504 todetermine the power and the transport block size to utilize on thesingle stream transmission.

Further, in this example, the scheduling signaling 508 may indicate thatthe rank of the transmission is rank=2 corresponding to dual streams, byincluding in the E-AGCH a primary scheduling grant (T/P)₁ and asecondary scheduling grant (T/P)₂. Here, the primary scheduling grant(T/P)₁ may be utilized to determine the transport block size for theprimary stream, while the secondary scheduling grant (T/P)₂ may beutilized to determine the transport block size for the secondary stream.Further, the primary scheduling grant (T/P)₁ may be utilized todetermine the total amount of power for the primary stream, and thetotal amount of power for the secondary stream may be set to be equal tothat of the primary stream. Table 1 below illustrates the relationshipdescribed here, wherein the primary scheduling grant (T/P)₁ is utilizedto determine the power level of the primary stream, the power level ofthe secondary stream, and the transport block size of the primarystream; while the secondary scheduling grant (T/P)₂ is utilized todetermine the transport block size of the secondary stream.

TABLE 1 Secondary Scheduling Primary Scheduling Grant (T/P)₁ Grant(T/P)₂ Power Level of Primary Stream Transport Block Size of Power Levelof Secondary Stream Secondary Stream Transport Block Size of PrimaryStreamE-TFC Selection, Power of Data Channels

FIG. 6 is a block diagram further illustrating a portion of atransmitter in a UE 210 configured for MIMO operation at the PHY layer306 in accordance with some aspects of the disclosure. In an aspect ofthe present disclosure as illustrated in FIG. 7, when the rank of thetransmission is rank=2, the power of the S-E-DPDCH(s) 620, correspondingto the secondary transport block, may be set to be equal to the power ofthe E-DPDCH(s) 624, corresponding to the primary transport block. Thatis, while some examples may utilize an asymmetric allocation of totalavailable power on the E-DCH between the first stream 610 and the secondstream 612, in those examples there may be some difficulty accuratelyestimating the powers of the eigenvalues and sufficiently quicklyadapting the power allocation. Further, dynamic and asymmetric powerallocation between the streams may lead to an increase in Node Bscheduler complexity, in that it may be required to evaluate differentcombinations of transport block sizes across the two streams such thatthe throughput can be maximized. Thus, in aspects of the presentdisclosure, as illustrated in FIG. 7, the sum total power on the firststream 610 may be equal to the sum total power on the second stream 612.Such an equal distribution of power amongst the streams may not beintuitive, since each stream is generally independently controllable dueto the utilization of separate power amplifiers corresponding to each ofthe streams. However, utilization of the equal distribution as describedin this aspect of the present disclosure can simplify the schedulinggrant signaling and enable improved transmission performance.

For example, in an aspect of the present disclosure, schedulingsignaling 508 received at the UE 210 and carried by the E-AGCH may beprovided to the E-TFC selection entity 504 in the form of a primaryscheduling grant and a secondary scheduling grant. Here, each of theprimary and the secondary scheduling grants may be provided in the formof traffic to pilot power ratios, or (T/P)₁ and (T/P)₂, respectively.Here, the E-TFC selection entity 504 may utilize the primary schedulinggrant T/P₁ to determine the total amount of power to transmit on theE-DPDCH(s), relative to the current transmit power on the DPCCH. Thatis, the E-TFC selection entity 504 may utilize the primary schedulinggrant (T/P)₁ to compute the power of the E-DPDCH(s), and may further setthe power of the S-E-DPDCH(s) to the same value as that set for theE-DPDCH(s). In this fashion, symmetric power allocation among theprimary stream on the E-DPDCH(s) and the secondary stream on theS-E-DPDCH(s) may be achieved based on the primary scheduling grant(T/P)₁. Importantly, in this example, the secondary scheduling grant(T/P)₂ is not utilized to determine the power of the secondary stream.

FIG. 7 is a graph schematically illustrating power levels for certainchannels in accordance with some aspects of the present disclosure. FIG.8 includes a corresponding flow chart 800 illustrating an exemplaryprocess for setting the power levels. In this example, a first pilotchannel 622 (DPCCH) is configured to have a certain power level,illustrated as first pilot power 702. That is, while the DPCCH 622carries some control information, it may also act as a pilot, forchannel estimation purposes at the receiver. Similarly, in an uplinkMIMO configuration in accordance with an aspect of the presentdisclosure, the S-DPCCH 618 may carry certain control information andmay additionally act as a pilot for additional channel estimationpurposes at the receiver. In the present disclosure, the S-DPCCH may bereferred to variously as a secondary pilot channel or a secondarycontrol channel, in accordance with whether reference is being made tothe channel's control aspects or its pilot aspects.

Here, according to the process 800, in block 802 the UE 210 may receivescheduling signaling 508, e.g., including a primary scheduling grantcarried on the E-AGCH, where the primary scheduling grant includes afirst traffic to pilot power ratio (T/P)₁ 704. Further, in block 804 theUE 210 may receive scheduling signaling 508 including a secondaryscheduling grant, which includes a second traffic to pilot power ratio(T/P)₂. As described above, the respective first and second schedulinggrants may be jointly encoded on the E-AGCH, or in other aspects, anysuitable scheduling grant signaling may be utilized for carrying therespective traffic to pilot power ratios.

In block 806, the UE 210 may receive an offset value Δ_(T2TP), forindicating an power offset for a reference power level 710 relative tothe power of the first pilot channel 622 (DPCCH). In some examples, theoffset value Δ_(T2TP) may be provided by a network node such as the RNC206 utilizing Layer 3 RRC signaling. Here, the Δ_(T2TP) value may beadapted to enable the UE 210 to determine the reference power level 710,at which level the second pilot channel 618 (S-DPCCH) may be set whenboosted as described below. That is, an unboosted power level 702 forthe pilot channel of the secondary stream S-DPCCH 618 may be configuredto take the same power level as that of the first pilot channel DPCCH622 by default. Of course, within the scope of the present disclosure,the unboosted power level for the second pilot S-DPCCH 618 need not bethe same as the power level of the first pilot channel DPCCH 622.Further, the second pilot S-DPCCH 618 need not be at the unboosted powerlevel; that is, in an aspect of the present disclosure, the unboostedpower level for the second pilot S-DPCCH is a reference level fordetermining the power level of the second data channel S-E-DPDCH 620.Further, the power level of the S-DPCCH 618 may be boosted to thereference power level 710 in accordance with the offset value Δ_(T2TP).Additional information regarding the boosting of the power level of theS-DPCCH 618 is provided elsewhere in the present disclosure.

As illustrated, the first traffic to pilot power ratio (T/P)₁ 704 may beutilized by the E-TFC selection entity 504 to determine the power levelcorresponding to the sum of the powers on the first data channel, e.g.,the E-DPDCH(s) 624. That is, the first traffic to pilot power ratio(T/P)₁ 704 may provide a ratio, e.g., in decibels, which may be appliedto set the power level 706 corresponding to the sum of the powers on thefirst data channel(s) E-DPDCH(s) 624 relative to the power level 702 ofthe first pilot channel DPCCH 622.

Thus, in block 808, a transmitter in the UE 210 may transmit a primarystream 610, which may include the first data channel E-DPDCH(s) 624 andthe first pilot channel DPCCH 622, wherein the ratio between the powerlevel 706 of the first data channel E-DPDCH(s) 624 and the power level702 of the first pilot channel DPCCH 622 corresponds to the firsttraffic to pilot power ratio (T/P)₁ 704.

In the illustration of FIG. 7, the power level 708 corresponding to thesum of the power on the S-E-DPDCH(s) 620 is configured to be equal tothe power level 706 corresponding to the sum of the power on theE-DPDCH(s) 624. That is, the power of the first data channel E-DPDCH(s)624 and the power of the second data channel S-E-DPDCH(s) 620 may beequal to one another. Thus, in block 810, a transmitter in the UE 210may transmit a secondary stream 612, including a second data channelS-E-DPDCH(s) 620, such that a ratio between the power level 708 of thesecond data channel S-E-DPDCH(s) 620 and an unboosted power level 702 ofthe pilot channel of the secondary stream S-DPCCH 710 corresponds to thesame first traffic to pilot power ratio (T/P)₁ 704.

Here, in an aspect of the present disclosure, the first stream 610 andthe secondary stream 612 may be spatially separated streams of an uplinkMIMO transmission, which share the same carrier frequency.

E-TFC Selection, TBS

In a further aspect of the present disclosure, as described above, theprimary scheduling grant (T/P)₁ may be utilized to determine a packetsize (e.g., the primary transport block size) to be utilized on theprimary stream 610, and the secondary scheduling grant (T/P)₂ may beutilized to determine a packet size (e.g., the secondary transport blocksize) to be utilized on the secondary stream 612. Here, thedetermination of the corresponding packet sizes may be accomplished bythe E-TFC selection entity 504, for example, by utilizing a suitablelookup table to find a corresponding transport block size and transportformat combination in accordance with the signaled traffic to pilotpower ratio.

FIG. 8 includes a second flow chart 850 illustrating a process forsetting transport block sizes corresponding to the respective schedulinggrants in accordance with an aspect of the present disclosure. While theprocess 850 is illustrated as a separate process, aspects of the presentdisclosure may include a combination of the illustrated process steps,e.g., utilizing the power setting shown in process 800 in combinationwith the transport block size setting shown in process 850.

In blocks 852 and 854, in substantially the same fashion as describedabove in relation to process 800 blocks 802 and 804, the UE 210 mayreceive a primary scheduling grant and a secondary scheduling grantincluding a first traffic to pilot power ratio (T/P)₁ and a secondtraffic to pilot power ratio (T/P)₂, respectively. In block 856, theE-TFC selection entity 504 may determine a packet size to be utilized ina transmission on the primary stream 610 in accordance with the firsttraffic to pilot power ratio (T/P)₁. As described above, thedetermination of the packet size may be made by looking up a transportblock size that corresponds to the first traffic to pilot power ratio(T/P)₁ by utilizing, for example, a lookup table. Of course, anysuitable determination of the corresponding transport block size may beutilized in accordance with the present disclosure, such as applying asuitable equation, querying another entity for the transport block size,etc. In block 858, the E-TFC selection entity 504 may similarlydetermine a packet size to be utilized in a transmission on thesecondary stream in accordance with the second traffic to pilot powerratio (T/P)₂.

E-TFC Selection, Scaling

In a further aspect of the disclosure, the UE 210 may have a limit onits available transmit power for uplink transmissions. That is, if thereceived scheduling grants configure the UE 210 to transmit below itsmaximum output power, the E-TFC selection algorithm may be relativelyeasy, such that the EUL transport format combination for each MIMOstream can simply be selected based on the serving grant for thatstream. However, there is a possibility that the UE 210 is powerheadroom limited. That is, the power levels for uplink transmissionsdetermined by the E-TFC selection entity 504 may configure the UE 210 totransmit at or above its maximum output power. Here, if the UE 210 ispower headroom limited, then in accordance with an aspect of the presentdisclosure, power and rate scaling may be utilized to accommodate bothof the streams.

That is, when the UE 210 is configured to select a MIMO transmission,the primary serving grant (T/P)₁ may be scaled by a constant (α) suchthat the UE's transmit power does not exceed the maximum transmit power.As described above, the primary serving grant (T/P)₁ may be utilized forselecting the power level of both the primary stream and the secondarystream; thus, scaling the primary serving grant (T/P)₁ in accordancewith the scaling constant α may accomplish power scaling of both thedata channels E-DPDCH and S-E-DPDCH. In turn, the scaling of the primaryserving grant (T/P)₁ additionally determines the power levels of theE-DPCCH and S-DPCCH, as well as the transport block size on the primarystream.

Further, the secondary serving grant (T/P)₂ may be scaled by the samescaling constant α. Here, the scaling of the secondary serving grant(T/P)₂ may determine the transport block size for the secondary stream.In this way, the E-TFC selection entity 504 can scale the transportblock size of the secondary stream by the same amount as the scaling ofthe transport block size of the primary stream. Thus, with the scalingof the power and transport block size of both streams, a symmetricreduction in accordance with the power headroom limit may be achieved.

Returning now to the process 850 illustrated in FIG. 8, the process oftransmitting the streams may include steps for scaling the power and/ortransport block size(s) as described above. That is, in block 860, theE-TFC selection entity 504 may scale the amount of power allocated tothe primary stream 610 and the secondary stream 612 in accordance with apower headroom limit. That is, in some examples where the scheduledpower is greater than or equal to the uplink power headroom limit, thepower for each of the primary and secondary streams may scaled by thescaling constant α to reduce the power to below the power headroomlimit.

In block 862, the process may determine a first scaled packet size, tobe utilized in a transmission on the primary stream 610 in accordancewith the scaled power. That is, in some examples the E-TFC selectionentity 504 may scale the transport block size for the primary stream 610in accordance with the scaled power. For example, the primary servinggrant (T/P)₁ may be multiplied by the scaling constant α, such that thelooking up of the transport block size for the primary stream may resultin an accordingly smaller transport block size. In another example, thetransport block size selected by the E-TFC selection entity 504 maysimply be scaled by the scaling constant α. Of course, any suitablescaling of the transport block size for the primary stream 610 inaccordance with the scaled power may be utilized.

In block 864, the process may determine a second scaled packet size, tobe utilized in a transmission on the secondary stream 612. Here, thesize of the second scaled packet may be determined in accordance with αvalue obtained in a lookup table corresponding to the scaled power. Thatis, the scaling constant α may be utilized to scale the power, asdescribed above; and this scaled power may be utilized to determine acorresponding scaled packet size.

HARQ

Returning now to FIG. 5, in some aspects of the disclosure, a singleHARQ entity 506 may handle the MAC functions relating to the HARQprotocol for each of the plurality of streams in a MIMO transmission.For example, the HARQ entity 506 may store the MAC-i PDUs forretransmission if needed. That is, the HARQ entity 506 may include aprocessing system 2014 including a memory 2005 storing packets as neededfor HARQ retransmissions of packets the receiver was unable to decode.Further, the HARQ entity 506 may provide the E-TFC, the retransmissionsequence number (RSN), and the power offset to be used by Layer 1 (PHY)306 for the transport blocks transmitted in a particular TTI. The HARQentity 506 may execute one HARQ process per E-DCH per TTI for singlestream transmissions, and may execute two HARQ processes per E-DCH perTTI for dual stream transmissions.

HARQ information transmitted from the Node B 208, such as ACK/NACKsignaling 510 for the primary and secondary transport blocks, may beprovided to the HARQ entity 506 over the E-DCH HARQ Indicator Channel(E-HICH). Here, the HARQ information 510 may include the HARQ feedbackcorresponding to the primary and secondary transport blocks from theNode B 208 to the UE 210. That is, the UE 210 may be allocated tworesources on the E-HICH such that the E-HICH can carry HARQ feedback foreach of the transport blocks transmitted in a primary and a secondaryHARQ process. For example, a secondary E-HICH ACK indicator may beallocated on the channelization code on which the primary E-HICH ACKindicator is allocated. In this example, the UE 210 de-spreads a singleSF=128 channelization code as in conventional HSUPA without uplink MIMO,however, the UE 210 monitors another orthogonal signature sequence indexin order to process the secondary E-HICH ACK indicator.

Physical Channels

Returning again to FIG. 6, the physical channels 602 may be combinedwith suitable channelization codes, weighted with suitable gain factors,mapped to a suitable I or Q branch at spreading blocks 604, and groupedby summing blocks 604 into virtual antennas 610, 612. In various aspectsof the present disclosure, the primary virtual antenna 610 may bereferred to as a primary stream, and the secondary virtual antenna 610may be referred to as a secondary stream. In the illustrated example,the streams 610 and 612 are fed into a virtual antenna mapping entity605. Here, the virtual antenna mapping entity 605 is configured to mapthe first stream 610 and the second stream 612 to spatially separatedphysical antennas 606 and 608, utilizing a configuration that may beadapted for power balancing between the respective physical antennas 606and 608.

In the illustrated example, one or more precoding vectors may beexpressed utilizing precoding weights, e.g., w₁, w₂, w₃, and w₄. Here,the spread complex valued signals from the virtual antennas 610, 612 maybe weighted utilizing a primary precoding vector [w₁, w₂] and asecondary precoding vector [w₃, w₄], respectively, as illustrated inFIG. 6. Here, if the UE 210 is configured to transmit a single transportblock in a particular TTI, it may utilize the primary precoding vector[w₁, w₂] for weighting the signal; and if the UE 210 is configured totransmit dual transport blocks in a particular TTI, the UE may utilizethe primary precoding vector [w₁, w₂] for virtual antenna 1, 610, andthe secondary precoding vector [w₃, w₄] for virtual antenna 2, 612. Inthis way, when the UE 210 transmits a single stream only, it may easilyfall back to closed loop beamforming transmit diversity, which may bebased on maximum ratio transmission, wherein the single stream istransmitted on the strong eigenmode or singular value. On the otherhand, the UE 210 may easily utilize both precoding vectors for MIMOtransmissions.

That is, in an aspect of the disclosure, the primary stream includingthe E-DPDCH(s) 624 may be precoded utilizing the primary precodingvector [w₁, w₂] while the secondary stream including the S-E-DPDCH(s)620 may be precoded utilizing the secondary precoding vector [w₃, w₄].

Further, allocation of the various physical channels 602 other than theE-DPDCH(s) 624 and the S-E-DPDCH(s) 620 between the primary stream 610and the secondary stream 612 can determine various characteristics andeffectiveness of the MIMO transmission. In accordance with one aspect ofthe disclosure, a primary pilot channel DPCCH 622 may be precodedutilizing the primary precoding vector, and a secondary pilot channelS-DPCCH 618 may be precoded along with the S-E-DPDCH(s) 620 utilizingthe secondary precoding vector, which may be orthogonal to the primaryprecoding vector. In some aspects of the present disclosure, the S-DPCCH618 may be transmitted on a different channelization code than thatutilized for the DPCCH 622; or the S-DPCCH 618 may be transmitted on thesame channelization code than that utilized for the DPCCH 622, byutilizing an orthogonal pilot pattern.

Here, the S-DPCCH 618 may be utilized as a reference, along with theDPCCH 622, to help sound the channel between the two UE transmitantennas 606, 608, and the Node B receiver antennas. By estimating theMIMO channel matrix between the UE 210 and the Node B 208 in accordancewith these reference signals, the Node B 208 may derive one or moresuitable precoding vectors that may accordingly be sent back to the UE210. For example, feedback from the Node B 208 that includes uplinkprecoding information may be 1-2 bits per slot (or any other suitablebit length) carried on the F-DPCH or the E-F-DPCH. Here, the precodinginformation may be provided alongside, or in the place of, the transmitpower control (TPC) bits conventionally carried on these channels.

Further, when the second stream is transmitted, the secondary pilotS-DPCCH 618 may serve as a phase reference for data demodulation of thesecond stream.

When utilizing precoded pilots 622 and 618, the Node B 208 may requireknowledge of the applied precoding vectors in order to compute newprecoding vectors. This is because the Node B 208 may need to undo theeffect of the applied precoding vectors in order to estimate the rawchannel estimates, based upon which the new precoding vectors arederived. However, knowledge at the Node B 208 of the precoding vectorsis generally not required for data demodulation, because the pilots,which serve as a reference to their respective data channels, see thesame channel as the data, since both the pilot and the data channels(primary and secondary) are precoded utilizing the same precodingvector. Further, applying precoding to the pilot channels 622 and 618can simplify soft handover. That is, it is relatively difficult fornon-serving cells to know the precoding vectors, while the serving cellknows the precoding vectors because it is the node that computes theprecoding vectors and sends them to the transmitter.

In a further aspect of the present disclosure, the primary virtualantenna 610, to which the primary precoding vector [w₁, w₂] is applied,may be utilized for transmitting the DPDCH 626, HS-DPCCH 628, andE-DPCCH 614, since the primary precoding vector [w₁, w₂] represents thestronger eigenmode. That is, transmitting these channels utilizingvirtual antenna 1 can improve the reliability of reception of thesechannels. Further, in some aspects of the disclosure, the power of thecontrol channel E-DPCCH 614 may be boosted, and may be utilized as aphase reference for data demodulation of the E-DPDCH(s) 624.

In some examples, an S-E-DPCCH 616 may be provided on the primaryvirtual antenna 610 as well. That is, in an aspect of the disclosure,control information for decoding the primary transport block carried onthe E-DPDCH(s) 624 may be encoded onto the E-DPCCH 614 utilizing aconventional E-DPCCH channel coding scheme, essentially according tolegacy EUL specifications for non-MIMO transmissions. Further, controlinformation for the secondary transport block may be encoded onto theS-E-DPCCH 616 utilizing a conventional E-DPCCH channel coding schemeaccording to the legacy EUL specifications for non-MIMO transmissions.Here, the E-DPCCH 614 and the S-E-DPCCH 616 may both be transmitted overthe first virtual antenna 610 and precoded utilizing the primaryprecoding vector [w₁, w₂]. In another example within the scope of thepresent disclosure, the S-E-DPCCH 616 may be transmitted on the secondvirtual antenna 612 and precoded utilizing the secondary precodingvector [w₃, w₄]; however, because the primary precoding vectorrepresents the stronger eigenmode, in order to improve the reliabilityof the reception of the S-E-DPCCH, its transmission over the primaryprecoding vector may be preferable.

In accordance with another aspect of the disclosure, as indicated by thedashed lines in FIG. 6, a separate S-E-DPCCH 616 is optional, and someaspects of the present disclosure omit the transmission of an S-E-DPCCH616 separate from the E-DPCCH 614. That is, the E-DPCCH controlinformation associated with the secondary transport block (S-E-DPCCH)may be provided on the E-DPCCH 614. Here, the number of channel bitscarried on the E-DPCCH 614 may be doubled from 30 bits, as utilized in3GPP Release-7 to 60 bits. To accommodate the additional controlinformation carried on the E-DPCCH 614, certain options may be utilizedin accordance with various aspects of the present disclosure. In oneexample, I/Q multiplexing of the E-DPCCH information for both of thetransport blocks may be used to enable transmission of the E-DPCCHinformation for both transport blocks on the same channelization code.In another example, the channel coding utilized for encoding the E-DPCCHmay utilize a reduced spreading factor, i.e., SF=128, to accommodate thedoubling of the channel bits. In still another example, a suitablechannelization code may be utilized to enable the encoding of theinformation onto the channel while maintaining the spreading factorSF=256.

FIG. 9 is a flow chart illustrating the generation of data informationand its associated control information in accordance with some aspectsof the present disclosure. In block 902, as illustrated in FIG. 4, theprocess may generate two transport blocks 402 and 452 to be transmittedon a primary data channel, e.g., the E-DPDCH(s) 624, and a secondarydata channel, e.g., the S-E-DPDCH(s) 620, respectively, during aparticular TTI. In block 904, the process may generate a primary controlchannel adapted to carry information associated with both the primarydata channel and the secondary data channel. For example, the UE 210 mayinclude a processing system 2014 configured to generate an E-DPCCH 614adapted to carry control information for both the E-DPDCH(s) 624 and theS-E-DPDCH(s) 620.

In one example, the generation of the primary control channel E-DPCCH614 in block 904 may include encoding 10 bits (or any suitable number ofcontrol bits) of control information for each data channel, utilizingtwo independent channel coding schemes. For example, legacy E-DPCCHchannel coding as utilized in Release-7 3GPP HSUPA specifications may beutilized, for control information corresponding to the E-DPDCH(s) 624and independently, for control information corresponding to theS-E-DPDCH(s) 620. As described above, to accommodate the additionalinformation to be carried on the primary control channel E-DPCCH 614,the spreading factor may be reduced to SF=128, I/O multiplexing may beutilized, or a suitable channelization code may be chosen to enable anencoding of the additional information utilizing the conventionalspreading factor SF=256.

In block 906, the process may apply the first precoding vector to theprimary data channel. For example, as illustrated in FIG. 6, the primarydata channel, i.e., E-DPDCH(s) 624, is sent into the first virtualantenna 610, and is precoded utilizing the primary precoding vector [w₁,w₂]. In block 908, the process may apply the secondary precoding vector[W₃, W₄], which is adapted to be orthogonal to the first precodingvector, to the secondary data channel. For example, the secondary datachannel, i.e., S-E-DPDCH(s) 620, is sent into the second virtual antenna612, and is precoded utilizing the secondary precoding vector [w₃, w₄].Here, the secondary precoding vector [w₃, w₄] may be adapted to beorthogonal to the primary precoding vector [w₁, W₂].

In block 910, the process may apply the first precoding vector to theprimary control channel, which is adapted to carry the informationassociated with both the primary data channel and the secondary datachannel. That is, in an aspect of the present disclosure, the secondtransport block, which is sent over the second virtual antenna 612, isprecoded utilizing a different precoding vector than the one utilizedfor precoding the control information associated with the secondtransport block. Here, the control information for both the transportblocks may be transmitted utilizing the primary precoding vector, sincethe primary precoding vector provides the stronger eigenmode of the MIMOchannel.

In block 912, the process may transmit the primary data channel and theprimary control channel utilizing the first virtual antenna 610; and inblock 914, the process may transmit the secondary data channel utilizingthe second virtual antenna 612.

Uplink Control Channel Boosting

Returning now to FIG. 5, as discussed above, when rank=2 is selectedindicating a MIMO transmission, the HARQ entity 506 may provide a poweroffset for each of the primary and secondary transport blocks. That is,when transmitting the dual streams, the power utilized for the data andcontrol channels may be boosted in accordance with a suitable offset.

For example, the range of power offsets for the secondary stream on thesecondary virtual antenna 612 might be expected to be similar to therange of power offsets for the primary stream on the primary virtualantenna 610. As a result, in some aspects of the present disclosure,existing methods defined in the 3GPP specifications for HSUPA forcomputing a power offset for the E-DPDCH(s) 624 can be re-used tocompute the power offset for the S-E-DPDCH(s) 620. Alternatively, inanother aspect of the disclosure, rather than re-using the samecomputational method for each virtual antenna the same reference gainfactor may be applied to both the primary data channel E-DPDCH(s) 624and the secondary data channel S-E-DPDCH(s) 620. Here, there may be noneed to signal a separate set of reference gain factors for thesecondary stream on the secondary virtual antenna 612. In this way, thepower of the secondary data channel S-E-DPDCH(s) 620 may take a fixedoffset relative to the power of the primary data channel E-DPDCH(s) 624.Here, the offset can be zero, i.e., setting the same power for therespective data channels, or nonzero, indicating different power levelsfor the respective data channels. Selection of the same power level foreach of the primary data channel E-DPDCH(s) 624 and the secondary datachannel S-E-DPDCH(s) 620 can ensure that the power across the twostreams is equally distributed.

As discussed above, uplink MIMO in accordance with various aspects ofthe present disclosure may introduce two new control channels: asecondary control channel (the S-DPCCH 618) and a secondary enhancedcontrol channel (the S-E-DPCCH 616). Among these channels, in an aspectof the disclosure the secondary control channel S-DPCCH 618 may beprovided on the secondary virtual antenna 612, as discussed above. Here,the secondary control channel S-DPCCH 618 can be utilized incoordination with the primary control channel DPCCH 622 for channelestimation of the MIMO channel at the receiver, e.g., the Node B 208.

In 3GPP Release-7 specifications, with the introduction of HSUPA,boosting of the enhanced control channel E-DPCCH was introduced tosupport the high data rates on the uplink. That is, in HSUPA, the pilotset point, that is, the Ecp/Nt could be varied by as much as 21.4 dB inaccordance with variations in the data rate. The boosted power level ofthe E-DPCCH serves as an enhanced pilot reference when high data ratesare used.

In a further aspect of the present disclosure, when rank=2 is selectedsuch that the secondary stream is transmitted over the secondary virtualantenna 612, the secondary control channel S-DPCCH 618 may serve as aphase reference for data demodulation of the S-E-DPDCH(s) 620. Becausethe secondary control channel S-DPCCH 618 may serve as the phasereference, as the data rate or the transport block size of the secondarytransport block carried on the secondary data channel S-E-DPDCH(s) 620increases, the power for the secondary control channel S-DPCCH 618 mayaccordingly be boosted. That is, in a similar fashion to the boosting ofthe enhanced control channel E-DPCCH 614 as utilized in Release-7 HSUPA,known to those skilled in the art, in some aspects of the presentdisclosure boosting of the secondary control channel S-DPCCH 618 may beutilized to support high data rate transmission on the secondary streamutilizing the secondary virtual antenna 612.

More specifically, one aspect of the disclosure boosts the S-DPCCH basedon the same parameters utilized for the boosting of the E-DPCCH. Thatis, an offset value β_(s-c) for boosting the power for the secondarycontrol channel S-DPCCH 618 in a particular TTI may correspond to apacket size of a packet transmitted on the enhanced primary data channelE-DPDCH(s) during that TTI. Here, the offset for boosting the power ofthe secondary control channel S-DPCCH may correspond to the packet sizeof the primary transport block sent over the E-DPDCH(s) 624.

Such a relationship between the boosting of a pilot on the secondaryvirtual antenna and a packet size sent on the primary virtual antennamay be counter-intuitive, since it may seem more natural to boost thesecondary control channel S-DPCCH 618 in accordance with the packet sizeof the secondary transport block sent over the secondary data channelS-E-DPDCH(s) 620. However, in accordance with an aspect of the presentdisclosure, to simplify the signaling the boost may be determined with apacket size on the other stream.

Here, the term “offset” may correspond to a scaling factor, which may bemultiplied with an unboosted value of the power. Here, in a decibelscale, the offset may be a decibel value to be added to the unboostedvalue of the power in dBm.

In one aspect of the present disclosure, the offset for the S-DPCCH maybe in accordance with the equation:

$\beta_{{s - c},i,{uq}} = {\beta_{c} \cdot \sqrt{{\max( {A_{ec}^{2},{\frac{\sum\limits_{k = 1}^{k_{\max,i}}\;( \frac{\beta_{{ed},i,k}}{\beta_{c}} )^{2}}{10^{\frac{\Delta_{T\; 2T\; P}}{10}}} - 1}} )},}}$wherein:

-   -   β_(s-c,i,uq) is the unquantized S-DPCCH power offset, in dB, for        the i^(th) E-TFC;    -   β_(c) is an additional gain factor for the DPCCH for a        particular TFC, as described in 3GPP TS 25.214 v10.3;    -   A_(ec) is a quantized amplitude ratio defined in 3GPP TS 25.213        v10.0 subclause 4.2.1.3;    -   k_(max,i) is the number of physical channels used for the i^(th)        E-TFC;    -   β_(ed,i,k) is an E-DPDCH gain factor for the i^(th) E-TFC on the        k^(th) physical channel; and    -   Δ_(T2TP) is a traffic to total pilot power offset configured by        higher layers, defined in 3GPP TS 25.213 v10.0 subclause        4.2.1.3.

In a further aspect of the present disclosure, when rank=1 is selectedsuch that a single stream is transmitted, the S-DPCCH 618 may betransmitted utilizing a single stream offset Δ_(sc) relative to theDPCCH 622. In this manner, if the UE 210 were configured for singlestream transmissions, as it would be for uplink CLTD transmissions, orif the UE 210 were primarily transmitting a single stream, theadditional pilot overhead due to the S-DPCCH 618 can be reduced.

FIG. 10 is a flow chart illustrating an exemplary process for wirelesscommunication by a UE 210 in accordance with an aspect of the disclosureutilizing boosting of the secondary pilot channel.

In block 1002, the process generates a primary transport block 402 fortransmission during a particular TTI. In block 1004, the processtransmits an enhanced primary data channel E-DPDCH 624 for carrying theprimary transport block 402, and transmits a primary control channelDPCCH 622, each on the first virtual antenna 610. In block 1006, theprocess determines a reference power level corresponding to thesecondary control channel S-DPCCH 618. In some examples, the referencepower level may be the same power level as the power level 702 of theprimary control channel DPCCH 622. In some other examples, the referencepower level may be offset relative to the power level 702 of the primarycontrol channel.

In block 1008, the process determines the rank of the transmission.Here, the rank may be determined in accordance with the grant receivedon the E-AGCH, as described above. If the rank is rank=2, then in block1010, the process generates a secondary transport block 452 fortransmission during the same TTI as that of the primary transport block402. In block 1012, the process transmits an enhanced secondary datachannel S-E-DPDCH 620 for carrying the secondary transport block 452 onthe second virtual antenna 612. Here, the enhanced secondary datachannel S-E-DPDCH 620 carries the secondary transport block 452 duringthe same TTI as that for the transmission of the primary transport block402 on the first virtual antenna 610. In block 1014, the processtransmits the secondary control channel S-DPCCH on the second virtualantenna 612 at a boosted power level relative to the reference powerlevel determined in block 1006. In some aspects of the disclosure, thedifference between the reference power level and the boosted power levelmay be determined in accordance with a size of the primary transportblock 402 transmitted on the enhanced primary data channel E-DPDCH 624.For example, the boosted power level may be determined by determiningthe product of the reference power level and the offset value β_(s-c) asdescribed above.

On the other hand, if the process determines in block 1008 that the rankis rank=1, then in block 1016 the process may transmit the secondarycontrol channel S-DPCCH 618 on the second virtual antenna 612 at asecond power level, which is offset by a certain amount (e.g., apredetermined amount) such as the single stream offset Δ_(sc) relativeto the power of the primary control channel DPCCH 622. Here, because therank is rank=1, the process may cease transmitting the enhancedsecondary data channel S-E-DPDECH 620. Here, the secondary controlchannel S-DPCCH 618 may be easily determined and may be available forsingle stream transmissions such as uplink closed loop transmitdiversity. In this manner, with a suitable selection of the singlestream offset Δ_(sc), the additional pilot overhead due to the secondarycontrol channel S-DPCCH 618 can be reduced.

Uplink Inner Loop Power Control

In HSUPA, active uplink power control is utilized to improve receptionof transmissions from mobile stations at the Node B. That is, the natureof the WCDMA multiple access air interface, wherein multiple UEssimultaneously operate within the same frequency separated only by theirspreading codes, can be highly susceptible to interference problems. Forexample, a single UE transmitting at a very high power can block theNode B from receiving transmissions from other UEs.

To address this issue, conventional HSUPA systems generally implement afast closed-loop power control procedure, typically referred to as innerloop power control. With inner loop power control, the Node B 208estimates the Signal-to-Interference Ratio (SIR) of received uplinktransmissions from a particular UE 210 and compares the estimated SIR toa target SIR. Based on this comparison with the target SIR, the Node B208 can transmit feedback to the UE 210 instructing the UE 210 toincrease or decrease its transmission power. The transmissions occuronce per slot, resulting in 1500 transmissions per second. Foradditional control, as described further below, the target SIR can bevaried by utilizing outer loop power control based on whethertransmissions meet a Block Error Rate (BLER) target.

With uplink MIMO in accordance with an aspect of the present disclosure,uplink inner loop power control may be improved by taking into accountadditional considerations. For example, due to the nonlinear processingof the MIMO receiver at the Node B 208, it may be desired that the powerper code remains substantially constant during the entire TTI. That is,variation in the power on the EUL traffic channels (i.e., the E-DPDCH(s)624 and the S-E-DPDCH(s) 620) across a TTI can affect schedulingdecisions at the Node B 208 in terms of the serving grants, as well asdata demodulation performance. However, since a TTI lasts three slots,adjustment of the power control every slot may not be desired. Thus, inaccordance with some aspects of the present disclosure, when uplink MIMOis configured, the power control may be performed once every threeslots, resulting in 500 transmissions per second (500 Hz) while stillenabling a constant transmit power on the traffic channels during theTTI on both of the streams.

On the other hand, additional channels transmitted on the uplink, suchas the DPDCH 626, E-DPCCH 614, and HS-DPCCH 628 can benefit from thefaster power control, i.e., with power control transmissions once perslot at 1500 Hz. Thus, in accordance with a further aspect of thepresent disclosure, the power control of the pilot channels and that thetraffic channels may be de-coupled. That is, a two-dimensional powercontrol loop may be implemented wherein the available traffic power andpilot powers are independently power controlled. In this manner, thepilot powers may be adjusted to ensure that overhead and DCH performanceis maintained, while the traffic power (E-DPDCH(s) 624 and S-E-DPDCH(s)620) may be adjusted separately, all the while ensuring that the E-DPCCH614 and S-DPCCH 618 are maintained at a fixed power offset below thetraffic powers, since the E-DPCCH 614 and S-DPCCH 618 serve as phasereferences to the traffic power.

A further consideration regarding power control when uplink MIMO isconfigured relates to whether the two streams should be independentlycontrolled by way of dual inner loop power control, or whether the powercontrol for each of the streams should be linked by utilizing a singleinner loop power control. Those of ordinary skill in the art familiarwith MIMO theory will understand that, assuming a 2×2 Rayleigh fadingMIMO channel matrix, the weaker singular value has a much higher chanceof a deep fade, when compared with the stronger singular value. Here,the singular value corresponds to the power of the signal component whenthe SINR measurements at the receiver are performed on the precodedchannel (i.e., the virtual channel). In this case, substantial transmitpower may be wasted on the secondary pilot S-DPCCH 618 if an attempt ismade to invert the weaker eigenmode.

Therefore, assuming that each of the E-DPCCH 614 and the S-DPCCH 618 areboosted as described above, in order to ensure a high enough phasereference for the E-DPDCH(s) 624 and the S-E-DPDCH(s) 620, then a singleinner loop power control based on a measurement of the received power ofthe primary control channel DPCCH 622 may be sufficient.

That is, in accordance with an aspect of the present disclosure, singleinner loop power control may be utilized at the Node B 208 forcontrolling the power corresponding to both of the two transport blockswhen the UE 210 is configured for MIMO transmissions. Here, the powercontrol may be based on an SINR measurement corresponding to the primarycontrol channel DPCCH 622, which is transmitted on the primary stream610.

For example, FIG. 11 illustrates an exemplary process for a networknode, such as Node B 208 or potentially an RNC 206, to implement singleinner loop power control for an uplink MIMO stream in accordance withsome aspects of the present disclosure. Here, the process 1100 may beimplemented by a processing system 2014, e.g., configured for executinginstructions stored in a computer-readable medium 106. In anotherexample, the process 1100 may be implemented by the Node B 2110illustrated in FIG. 21. Of course, any suitable network node capable ofimplementing the described functions may be utilized within the scope ofthe present disclosure.

In the process 1100, in block 1102, the Node B 208 may receive an uplinktransmission from a UE 208, the transmission including a first stream610 having a primary data channel E-DPDCH 624 and a primary pilotchannel DPCCH 622, and second stream 612 having a secondary pilotchannel S-DPCCH 618 and optionally a secondary data channel S-E-DPDCH620. That is, the received uplink transmission may be a rank=1transmission that does not include the secondary data channel S-E-DPDCH620 or a rank=2 transmission including the secondary data channelS-E-DPDCH 620. In block 1104, the Node B 208 may determine an SIRcorresponding to the primary pilot channel DPCCH 622, received on thefirst stream. In block 1106, the Node B 208 may compare the SIRdetermined in block 1104 with an SIR target. For example, the SIR targetmay be a predetermined value stored in a memory. Further, the SIR targetmay be a variable controllable by the outer loop power control module orprocedure.

In block 1108, the Node B 208 may generate a suitable power controlcommand based on the comparison made in block 1106. Here, the generatedpower control command may be adapted to control a power of the firststream and a power of the second stream. For example, the power controlcommand may directly correspond to the primary pilot channel DPCCH 622,and may directly instruct a change in power of the primary stream.However, with a knowledge that the power of the second stream is linkedto the power of the primary stream, e.g., by being related by a fixedoffset, the power control command may control a respective power of bothstreams.

Here, a power level of the primary stream may include one or more of apower level of the dedicated physical control channel DPCCH 622, a powerlevel of the enhanced dedicated physical control channel E-DPCCH 624, apower level of the enhanced dedicated physical data channel E-DPDCH 624,or a sum of any or all of these channels. Similarly, a power level ofthe secondary stream may include one or more of a power level of thesecondary dedicated physical control channel S-DPCCH 618, a power levelof the secondary enhanced dedicated physical data channel S-E-DPDCH 620,or a sum of any or all of these channels.

FIG. 12 illustrates a process 1200 for inner loop power control inaccordance with some aspects of the present disclosure that may beimplemented by a UE 210. In some examples, the process 1200 may beimplemented by a processing system 2014, e.g., configured for executinginstructions stored in a computer-readable medium 106. In anotherexample, the process 1200 may be implemented by the UE 2150 illustratedin FIG. 21. Of course, any suitable mobile or stationary user equipment210 capable of implementing the described functions may be utilizedwithin the scope of the present disclosure.

In block 1202, the UE 210 may transmit an uplink transmission includinga primary stream 610 and a secondary stream 612. Here, the primarystream 610 may include a primary data channel E-DPDCH 624 and a primarypilot channel DPCCH 622. Further, the secondary stream 612 may include asecondary pilot channel S-DPCCH 618 and optionally a secondary datachannel S-E-DPDCH 620. That is, the transmitted uplink transmission maybe a rank=1 transmission that does not include the secondary datachannel S-E-DPDCH 620 or a rank=2 transmission including the secondarydata channel S-E-DPDCH 620.

In block 1204, the UE 210 may receive a first power control command. Insome examples, as described above, the power control command may betransmitted once each transmission time interval. Here, the first powercontrol command may be adapted for directly controlling a power of theprimary stream 610. Based on the received first power control command,in block 1206, the UE 210 may accordingly adjust the power of theprimary stream, for example, by adjusting the power of the primary pilotchannel DPCCH 622. Thus, in block 1208 the UE 210 may transmit theprimary stream 610 in accordance with the first power control command.That is, the UE 210 may utilize the adjusted primary pilot channel DPCCH622 power determined in block 1206, while maintaining a power level ofthe enhanced dedicated physical control channel E-DPCCH 614 and at leastone primary data channel E-DPDCH 624 at a second fixed offset relativeto the power of the dedicated physical control channel DPCCH 622.

In block 1210, the UE 210 may transmit the secondary stream 612,maintaining a power level of the secondary stream 612 at a first fixedoffset relative to the power of the primary stream 610. In this way, thesingle first power control command received in block 1204 may controlthe power of the primary stream 610 and the secondary stream 612.

FIG. 13 illustrates another exemplary procedure similar to that oneillustrated in FIG. 12, for implementation by a UE 210 in accordancewith some aspects of the present disclosure. In block 1302, the UE 210may transmit an uplink transmission including a primary stream 610 and asecondary stream 612. Here, the primary stream 610 may include a primarydata channel E-DPDCH 624 and a primary pilot channel DPCCH 622. Further,the secondary stream 612 may include a secondary pilot channel S-DPCCH618 and optionally a secondary data channel S-E-DPDCH 620. That is, thetransmitted uplink transmission may be a rank=1 transmission that doesnot include the secondary data channel S-E-DPDCH 620 or a rank=2transmission including the secondary data channel S-E-DPDCH 620.

In block 1304, the UE 210 may receive a first power control command onceeach TTI, the first power control command being adapted for controllinga power of the primary data channel E-DPDCH 624. In block 1306, the UE210 may receive a second power control command once per slot, the secondpower control command adapted for controlling a power of one or morecontrol channels carried on the primary stream 610. In block 1308, theprocess may adjust the power of the primary data channel E-DPDCH 624 inaccordance with the first power control command, and adjust the power ofthe primary pilot channel DPCCH 622 in accordance with the second powercontrol command. Thus, in block 1310, the UE 210 may transmit theprimary stream 610 in accordance with the first power control commandand the second power control command, as adjusted in block 1308. Inblock 1312, the UE 210 may transmit the secondary stream 612,maintaining a power level of the secondary stream 612 at a first fixedoffset relative to the power of the primary stream 610.

Outer Loop Power Control

In addition to the inner loop power control, an HSUPA network mayadditionally utilize outer loop power control. As briefly describedabove, outer loop power control may be utilized to adjust the SIR targetset point in the Node B 208 in accordance with the needs of theindividual radio link. Adjustment of the SIR target by utilizing theouter loop power control may aim for transmissions to meet a certainblock error rate (BLER) target. In one example, outer loop power controlcan be implemented by having the Node B 208 tag received uplink userdata with a frame reliability indicator, such as the result of a CRCcheck corresponding to the user data, before sending the frame to theRNC 206. Here, if the RNC 206 determines that the transmission qualityof uplink transmissions from the UE 210 is changing, the RNC 206 maycommand the Node B 208 to correspondingly alter its SIR target.

In an example utilizing single inner loop power control for uplink MIMOtransmissions as described above, adjustment of the SIR target as a partof the outer loop power control presents additional considerations. Forexample, in some aspects of the disclosure, adjustment of the SIR targetmay be based on BLER performance and/or HARQ failure performance of theprimary stream 610. This would appear to be a natural choice, given thatthe single inner loop power control as described above may be based onthe DPCCH 622, which may also be carried on the primary stream 610.Further, adjustment of the SIR target based on BLER performance and/orHARQ failure performance of the primary stream 610 may achieve a BLERtarget on the secondary stream 612 by maintaining an outer loop on therate control of the second stream 612.

In another aspect of the disclosure, adjustment of the SIR target may bebased on BLER performance and/or HARQ failure performance of thesecondary stream 612. Here, this approach may suffer from an issue inwhich the SIR target is continuously increased to overcome a deep fadeassociated with the weaker singular value of the MIMO channel, and couldresult in a situation wherein the BLER on the first stream is much lowerthan the BLER target, while the BLER target on the second stream may noteven be achieved.

In still another aspect of the disclosure, adjustment of the SIR targetmay be based on BLER performance and/or HARQ failure performance of boththe primary stream 610 and the secondary stream 612. For example, theSIR target may be adjusted in accordance with a suitable weightedfunction of the BLER performance and/or the HARQ failure performance ofeach MIMO stream. With appropriate weighting in such a function, the SIRtarget might be biased in favor of the primary stream while still payingsome attention to the performance of the secondary stream, orvice-versa. This example may be helpful in a situation in which theouter loop on rate control in the Node B scheduler finds it challengingto meet a certain BLER target or HARQ failure target on one or the otherstream.

Particular examples in which the SIR target is adjusted based at leastin part on the BLER performance and/or the HARQ failure performance ofboth the primary stream and the secondary stream may be implemented inaccordance with the process illustrated by the flow chart of FIG. 14.Here, the process may be implemented by an RNC 206, or at any othersuitable network node coupled to the Node B 208. Performance of theprocess at an RNC 206 or other network node other than the Node B 208can improve performance in the case of a soft handover betweenrespective Node Bs. However, other examples in accordance with aspectsof the present disclosure may implement the illustrated process at theNode B 208.

As described above, when the Node B 208 receives uplink transmissions itmay calculate a CRC and compare it to a CRC field in the data block.Thus, in block 1402, the RNC 206 may receive the results of the CRCcomparisons for each stream of the uplink MIMO transmission, e.g., overa backhaul connection between the Node B 206 and the RNC 206. In block1404, in accordance with the CRC results, the process may determine theBLER performance and/or the HARQ failure performance of at least one ofthe primary stream 610 or the secondary stream 612. In some examples, asdescribed above, the metric, e.g., the BLER performance and/or the HARQfailure performance may in fact be determined for both streams. Thus, inblock 1406, the process may generate a new SIR target in accordance withthe BLER performance and/or the HARQ failure performance determined inblock 1004, for at least one of the primary stream or the secondarystream, and in block 1408, the process may send the generated SIR targetto the Node B 208. In this way, by virtue of the utilization of a singleinner loop power control for both streams, the generation of a singleSIR target can be sufficient for control of the power on both of thestreams.

Uplink Scheduler

Yet another consideration with an uplink MIMO system in accordance withan aspect of the present disclosure relates to the design of the uplinkscheduler. While an uplink scheduler has several aspects, one particularaspect of the MIMO uplink scheduler decides between scheduling singlestream or dual stream uplink transmissions. Here, one metric that mightbe utilized in making a determination of whether to schedule the singlestream or the dual stream is the throughput that can be achieved using asingle stream, and the sum throughput that can be achieved using dualstreams.

That is, if the UE 210 is transmitting a single stream, as describedabove, to reduce the overhead for the secondary pilot channel S-DPCCH618, its power may be offset with respect to the power of the primarypilot channel DPCCH 622, by the single stream offset Δ_(sc). However, inan aspect of the present disclosure as described above, when data istransmitted on a second stream, the power of the secondary pilot channelS-DPCCH 618 may be boosted. Thus, to evaluate the dual stream throughputthat might be achieved if the UE 210 is to transmit dual streams, inaccordance with an aspect of the present disclosure the Node B 208 maytake into account the boosting of the secondary pilot channel S-DPCCH618 when the UE 210 is configured to transmit two streams. That is, thescheduler at the Node B 208 may estimate the traffic signal to noiseratio that would have resulted from a different transmit pilot powerlevel than the one actually sent.

A further consideration for a scheduler that must deal with potentialswitching between single stream transmissions and dual streamtransmissions relates to HARQ retransmissions. For example, HARQretransmissions might not occur instantaneously after the reception of anegative HARQ acknowledgment message. Further, the HARQ retransmissionmay fail as well and multiple HARQ retransmissions may be transmitted.Here, the HARQ retransmission period may take some time, and during theHARQ retransmission period a decision may be taken to change betweendual stream transmissions and single stream transmissions. In this case,in accordance with various aspects of the present disclosure thescheduler may consider certain factors to determine over which stream totransmit a HARQ retransmission.

In particular, there are three main scenarios that the scheduler mayconsider. In one scenario, if the UE 210 transmits a packet on a singlestream, that packet may fail and HARQ retransmissions of the failedpacket may occur one or more times. During the HARQ retransmissionperiod, the UE 210 may receive a command to switch to dual streamtransmissions, such as MIMO transmissions utilizing dual transportblocks. In another scenario, if the UE 210 transmits packets on dualstreams, the packet transmitted on the weak, secondary stream 612 mayfail and HARQ retransmissions of the failed packet may occur one or moretimes. During the HARQ retransmission period, the UE 210 may receive acommand to switch to single stream transmissions, such as CLTDtransmissions utilizing a single transport block. In yet anotherscenario, if the UE 210 transmits packets on dual streams, the packettransmitted on the stronger, primary stream 610 may fail and HARQretransmissions of the failed packet may occur one or more times. Duringthe HARQ retransmission period, the UE 210 may receive a command toswitch to single stream transmissions, such as CLTD transmissionsutilizing a single transport block. In each of these cases, thescheduler should consider whether to actually switch between single anddual streams, and if so, on which stream to send the HARQretransmissions. Each of these scenarios is discussed in turn below.

FIG. 15 is a flow chart illustrating an exemplary process 1500 for anuplink scheduler to follow when the UE 210 receives a command to switchfrom single stream to dual stream transmissions during a HARQretransmission period. Here, the process 1500 may take place within aprocessing system 2014, which may be located at the UE 210. In anotheraspect, the process 1500 may be implemented by the UE 2154 illustratedin FIG. 21. Of course, in various aspects within the scope of thepresent disclosure, the process 1500 may be implemented by any suitableapparatus capable transmitting a single stream uplink and a MIMO uplinkutilizing dual streams.

In accordance with the process 1500, in block 1502 the UE 210 maytransmit an uplink utilizing a single stream. For example, the UE 210may transmit a single transport block utilizing the E-DPDCH 624 in aCLTD mode, which may utilize both physical antennas 606 and 608 totransmit the single stream. Based on the single stream transmission inblock 1502, in block 1504 the UE 210 may receive HARQ feedbackindicating a decoding failure of the transmission at the receiver. Here,the HARQ feedback may include ACK/NACK signaling 510 provided to theHARQ entity 506 on the E-HICH, as described above. Thus, as describedabove, the HARQ entity 506 may determine to retransmit the failed MACPDU corresponding to the decoding failure. At or near this time, inblock 1506 the UE 210 may determine to transmit dual streams. Forexample, the UE 210 may receive a command from the network to switch toa dual stream mode for MIMO transmissions. In another example, the UE210 may determine to switch to the dual stream mode for MIMOtransmissions based on suitable criteria.

Thus, during the HARQ retransmission period during which the UE 210 isattempting to retransmit the failed packet, the uplink scheduler for theUE 210 must handle the retransmission as well as switch from the singlestream mode to the dual stream mode. An issue here is that the UE ispower-limited, and the grant of power for a dual stream transmissionmust be allocated between the two streams. Thus, if a packet that wasoriginally transmitted on a single stream is to be retransmitted on oneof the dual streams, the available E-DCH power for the retransmissionwould need to be reduced by a factor of two to accommodate the secondarystream.

Thus, in an aspect of the present disclosure, in block 1508, the UE 210may maintain the transmitting of the uplink utilizing the single stream.That is, despite the determination in block 1506 to switch to the dualstream mode, the UE 210 in accordance with an aspect of the presentdisclosure may hold off the changing to the dual stream mode until theHARQ retransmissions corresponding to the decoding failure are complete.

In block 1510, the UE 210 may receive further HARQ feedback 510corresponding to the transmission in block 1508. Here, if the HARQfeedback 510 received in block 1510 indicates a further decoding failureof the transmission in block 1508 by sending a negative acknowledgment(NACK), then the process may return to block 1508, continuing tomaintain the transmitting of the uplink utilizing the single stream.However, if the HARQ feedback 510 received in block 1510 indicates adecoding success by sending a positive acknowledgment (ACK), then inblock 1512 the UE 210 may transmit the uplink utilizing dual streams,e.g., as a MIMO transmission utilizing two transport blocks.

FIG. 16 is a flow chart illustrating an exemplary process 1600 for anuplink scheduler to follow when the UE 210 receives a command to switchfrom dual stream to single stream transmissions during a HARQretransmission period. Here, the process 1600 may take place within aprocessing system 2014, which may be located at the UE 210. In anotheraspect, the process 1600 may be implemented by the UE 2154 illustratedin FIG. 21. Of course, in various aspects within the scope of thepresent disclosure, the process 1600 may be implemented by any suitableapparatus capable transmitting a single stream uplink and a MIMO uplinkutilizing dual streams.

In accordance with the process 1600, in block 1602 the UE 210 maytransmit an uplink utilizing a first stream and a second stream. Here,the terms “first stream” and “second stream” are merely nominative, andeither stream may correspond to one of a primary stream sent on aprimary precoding vector 610 or a secondary stream sent on a secondaryprecoding vector 612. For example, one stream can include a primarytransport block on the data channel E-DPDCH(s) 624, and the other streamcan include a secondary transport block on the data channel S-E-DPDCH(s)620, which may be transmitted utilizing orthogonal precoding vectors[w₁, w₂] and [w₃, w₄], respectively. In this example, with theconfiguration illustrated in FIG. 6, the primary stream is the strongereigenmode, while the secondary stream is the weaker eigenmode.

Based on the dual stream transmission in block 1602, in block 1704 theUE 210 may receive HARQ feedback indicating a decoding failure of apacket on the first stream and a decoding success of a packet on thesecond stream. Here, the HARQ feedback may include ACK/NACK signaling510 provided to the HARQ entity 506 on the E-HICH, as described above.The HARQ feedback may thus include a positive acknowledgment (ACK) forone of the streams, and a negative acknowledgment (NACK) for the otherstream. Thus, as described above, the HARQ entity 506 may determine toretransmit the failed MAC PDU corresponding to the decoding failure onthe secondary stream. For example, the packet transmitted utilizing theprimary precoding vector 610 may fail, corresponding to the reception ofa negative acknowledgment (NACK) while the packet transmitted utilizingthe secondary precoding vector 612 may succeed, corresponding to thereception of a positive acknowledgment (ACK). As another example, thepacket transmitted utilizing the primary precoding vector 610 maysucceed, corresponding to the reception of a positive acknowledgment(ACK) while the packet transmitted utilizing the secondary precodingvector 612 may fail, corresponding to the reception of a negativeacknowledgment (NACK).

At or near this time, in block 1610 the UE 210 may determine to transmita single stream. For example, the UE 210 may receive a command from thenetwork to switch to a single stream mode, e.g., for CLTD transmissions.In another example, the UE 210 may determine to switch to the singlestream mode based on suitable criteria.

Thus, during the HARQ retransmission period during which the UE isattempting to retransmit the failed packet transmitted on the firststream, the uplink scheduler for the UE 210 must handle theretransmission as well as switch from the dual stream mode to the singlestream mode.

In an aspect of the present disclosure, in block 1608, the UE 210 mayallocate power from the second stream, corresponding to the packet thatwas successfully decoded, to the first stream, corresponding to thedecoding failure. In this way, the single stream transmission may havean increased power relative to a power of either of the dual streamstransmitted in the dual stream mode, improving the likelihood of asuccessful decoding of the following retransmission. In some examples,all available power on the E-DCH may be allocated to the first stream.That is, in block 1610, the UE 210 may transmit a HARQ retransmissioncorresponding to the decoding failure on the first stream, on the firststream. That is, the precoding vector that was utilized for thetransmission of the packet that failed, may be utilized for the singlestream retransmission of the packet after switching to the single streammode.

FIG. 17 is a flow chart illustrating another exemplary process 1700 foran uplink scheduler to follow when the UE 210 receives a command toswitch from dual stream to single stream transmissions during a HARQretransmission period. Here, the process 1700 may take place within aprocessing system 2014, which may be located at the UE 210. In anotheraspect, the process 1700 may be implemented by the UE 2154 illustratedin FIG. 21. Of course, in various aspects within the scope of thepresent disclosure, the process 1700 may be implemented by any suitableapparatus capable transmitting a single stream uplink and a MIMO uplinkutilizing dual streams.

The first blocks of process 1700 are similar to process 1600 illustratedin FIG. 16. That is, block 1702, 1704, and 1706 may be substantiallysimilar to those described above with respect to blocks 1602, 1604, and1606, and portions of these blocks that are the same as those describedabove will not be repeated. However, unlike process 1600, process 1700may provide a retransmitted packet on a different precoding vector thanthe precoding vector on which the packet was previously transmitted.Thus, in block 1708 the UE 210 may allocate power from the first stream,corresponding to the decoding failure, to the second stream,corresponding to the packet that was successfully decoded. In this way,similar to process 1600, the single stream transmission may have anincreased power relative to a power of either of the dual streamstransmitted in the dual stream mode, improving the likelihood of asuccessful decoding of the following retransmission. In some examples,all available power on the E-DCH may be allocated to the second stream.Thus, in block 1710, the UE 210 may transmit a HARQ retransmissioncorresponding to the decoding failure on the first stream, on the secondstream. That is, the precoding vector that was utilized for thetransmission of the packet that succeeded, may be utilized for thesingle stream transmission of the HARQ retransmission after switching tothe single stream mode. Thus, in an aspect of the present disclosure,after switching to the single stream mode, the packet that failed whentransmitted utilizing one precoding vector, may be retransmittedutilizing the other precoding vector.

In a further aspect of the present disclosure, a decision regardingwhether to change from the dual stream mode to the single stream modemay be made by the E-TFC selection entity 504. Here, the selection maycorrespond to various factors, such as the available power granted tothe UE 210 for its next uplink transmission, how much power might beneeded to carry a minimum supported transport block size for dual streamtransmissions, or the channel conditions. For example, when channelconditions are poor, it may be desirable to transmit a single streamonly, so as to increase the available power per stream. Further, ifsufficient power to carry a particular size transport block for dualstream transmissions is not available, it may be desirable to transmit asingle stream only. On the other hand, if the opportunity to utilizeboth streams is available, it may be generally desirable to transmitdual streams in uplink MIMO to increase the throughput.

For example, FIG. 18 illustrates another exemplary process 1800 foruplink scheduling in accordance with some aspects of the presentdisclosure. Here, the process 1800 may take place within a processingsystem 2014, which may be located at the UE 210. In another aspect, theprocess 1800 may be implemented by the UE 2154 illustrated in FIG. 21.Of course, in various aspects within the scope of the presentdisclosure, the process 1800 may be implemented by any suitableapparatus capable transmitting a single stream uplink and a MIMO uplinkutilizing dual streams.

In block 1802, the UE 210 transmits dual streams in an uplink MIMOtransmission. In block 1804, the UE 210 receives HARQ feedbackindicating a decoding failure on the stronger, primary stream 610 and adecoding success on the weaker, secondary stream 612. In this case, inaccordance with an aspect of the present disclosure, the UE 210 maydetermine whether to transmit a single stream or dual streams inaccordance with suitable factors. If a single stream is selected, thenin block 1806 the UE 210 may allocate all available power on the E-DCHto the primary precoding vector 610 as a single stream transmission, andin block 1808 the UE 210 may continue with the HARQ retransmissions ofthe packet utilizing the primary precoding vector 610. On the otherhand, if dual streams are selected, then in block 1810 the UE 210 maycontinue with the HARQ retransmissions of the packet utilizing theprimary precoding vector and begin transmission of a newly selectedpacket on the weaker, secondary precoding vector. That is, HARQretransmissions of the failed packet may continue on the streamcorresponding to the failed packet, and new packets may be selected fortransmission on the stream corresponding to the successful packet.

As another example, FIG. 19 illustrates another exemplary process 1900for uplink scheduling in accordance with some aspects of the presentdisclosure. Here, the process 1900 may take place within a processingsystem 2014, which may be located at the UE 210. In another aspect, theprocess 1900 may be implemented by the UE 2154 illustrated in FIG. 21.Of course, in various aspects within the scope of the presentdisclosure, the process 1900 may be implemented by any suitableapparatus capable transmitting a single stream uplink and a MIMO uplinkutilizing dual streams.

In block 1902, the UE 210 transmits dual streams in an uplink MIMOtransmission. In block 1904, the UE 210 receives HARQ feedbackindicating a decoding failure on the weaker, secondary stream 612 and adecoding success on the stronger, primary stream 610. In this case, inaccordance with an aspect of the present disclosure, in block 1906 theUE 210 may determine whether to transmit a single stream or dual streamsin accordance with suitable factors. If a single stream is selected,then in block 1908 the UE 210 may allocate all available power on theE-DCH to the secondary precoding vector as a single stream transmission,and in block 1910 the UE 210 may continue with the HARQ retransmissionsof the packet utilizing the secondary precoding vector 612.

On the other hand, if dual streams are selected in block 1906, then theE-TFC selection entity 504 may consider additional factors in thegeneration of the transmission in the next transmission time interval.For example, as described above the E-TFC selection entity 504 receivesscheduling signaling 508 such as an absolute grant for each of thetransport blocks 610 and 612 at a certain interval. Here, the intervalover which the scheduling grant is provided to the UE 210 may not be asoften as every transmission time interval. Therefore, in the currentscenario when deciding the packets to transmit on each stream in thenext transmission time interval, the E-TFC selection entity 504 may relyupon a scheduling grant received at some time in the past. Thescheduling grant provided on the E-AGCH generally provides a power foreach of the streams, and a transport block size for each of the streams.

In accordance with an aspect of the present disclosure, when dualstreams are selected after the receiving of the HARQ feedback in block1904 that indicates a decoding success on the primary precoding vector610 and a decoding failure on the secondary precoding vector 612, theE-TFC selection entity 504 may select a next packet to be transmitted onthe primary precoding vector 610 along with the retransmitted packetprovided by the HARQ entity 506 to be transmitted on the secondaryprecoding vector 612. Here, an uplink MIMO system in accordance withsome aspects of the present disclosure may be constrained by arequirement that the same orthogonal variable spreading factor (OVSF),or simply spreading factor, be utilized for both streams. However, inorder to utilize certain spreading factors, the transport block size inthe next selected packet may be required to have at least a certainminimum bit length. For example, a minimum transport block size for thenext selected packet may be 3988 bits, and if the next selected packetis to be transmitted utilizing the same spreading factor as theretransmitted packet on the secondary stream 612, the packet selectedfor the primary stream 610 must be greater than 3988 bits in length.

In a further aspect of the present disclosure, the E-TFC selectionentity 504 may take into account the power available for primary stream610 for the next transmission. That is, because the scheduling grantutilized for a particular transmission time interval that is to includea HARQ retransmission on the secondary stream 612 may have been grantedat some previous time, the selection of the following packet to transmiton the primary stream 610 may present issues with the uplink powerheadroom. Thus, the E-TFC selection entity 504 may consider whether theavailable power for the primary stream 610 is greater than a minimumpower to carry a minimum supported transport block size on the primarystream 610 for dual stream (e.g., rank=2 MIMO) transmissions.

Thus, returning to FIG. 19, if in block 1906 the UE 210 determines thatconditions may be favorable for dual stream rank=2 MIMO transmission,then in block 1912 the E-TFC selection entity 504 may select the nextpacket for transmission on the primary stream 610. In block 1914, theE-TFC selection entity 504 may determine whether the transport blocksize (TBS) of the packet selected in block 1912 is greater than aminimum transport block size. If not, then if the process is constrainedby the minimum transport block size requirement, then the process mayreturn to block 1908, and allocate all E-DCH power to the primaryprecoding vector 610 and block 1910 to retransmit the failed packetutilizing the secondary precoding vector in a single stream rank=1transmission.

However, in an aspect of the present disclosure, the UE 210 may beenabled to violate the general requirement for the minimum transportblock size. That is, despite the selected transport block size beingsmaller than the minimum transport block size, the E-TFC selectionentity 504 may nevertheless transmit the selected transport block on theprimary stream 610. Here, the transmission of the selected transportblock on the primary stream 610 may utilize a different spreading factorthan the retransmission on the secondary stream 612; or the spreadingfactor of the retransmission on the secondary stream 612 may be changedto match that one utilized for the new transport block to be transmittedon the primary stream 610, in accordance with a suitable designdecision.

In block 1916, the E-TFC selection entity 504 may determine whether theavailable power for the primary stream 610 is greater than a minimumpower to carry a minimum supported transport block size for dual streamtransmissions. Here, the minimum available power requirement may in factbe the same requirement described above, i.e., the minimum transportblock size requirement. That is, the available power may be insufficientto support the minimum transport block size. If the available power isnot greater than the minimum power, then if the process is constrainedby the minimum transport block size requirement, the E-TFC selectionentity 504 may return to blocks 1908 and 1910, as described above,retransmitting the failed packet utilizing the single stream.

However, in an aspect of the present disclosure, the UE 210 may beenabled to violate the general requirement for the minimum power. Thatis, despite the available power for the primary stream 610 not beinggreater than the minimum power to carry the minimum supported transportblock size for the dual stream transmissions, the process may proceed toblock 1918, wherein the UE 210 may transmit a new packet utilizing theprimary precoding vector 610, and retransmit the failed packet utilizingthe secondary precoding vector 612. Here, the transmitted packet mayhave a smaller transport block size than generally required by theminimum transport block size requirement, but at the smaller transportblock size the available power may be sufficient. In this case, asabove, the transmission of the selected transport block on the primarystream 610 may utilize a different spreading factor than theretransmission on the secondary stream 612; or the spreading factor ofthe retransmission on the secondary stream 612 may be changed to matchthat one utilized for the new transport block to be transmitted on theprimary stream 610, in accordance with a suitable design decision.

In accordance with various aspects of the disclosure, an element, or anyportion of an element, or any combination of elements may be implementedwith a “processing system” that includes one or more processors.Examples of processors include microprocessors, microcontrollers,digital signal processors (DSPs), field programmable gate arrays(FPGAs), programmable logic devices (PLDs), state machines, gated logic,discrete hardware circuits, and other suitable hardware configured toperform the various functionality described throughout this disclosure.

One or more processors in the processing system may execute software.Software shall be construed broadly to mean instructions, instructionsets, code, code segments, program code, programs, subprograms, softwaremodules, applications, software applications, software packages,routines, subroutines, objects, executables, threads of execution,procedures, functions, etc., whether referred to as software, firmware,middleware, microcode, hardware description language, or otherwise. Thesoftware may reside on a computer-readable medium. The computer-readablemedium may be a non-transitory computer-readable medium. Anon-transitory computer-readable medium includes, by way of example, amagnetic storage device (e.g., hard disk, floppy disk, magnetic strip),an optical disk (e.g., compact disk (CD), digital versatile disk (DVD)),a smart card, a flash memory device (e.g., card, stick, key drive),random access memory (RAM), read only memory (ROM), programmable ROM(PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), aregister, a removable disk, and any other suitable medium for storingsoftware and/or instructions that may be accessed and read by acomputer. The computer-readable medium may also include, by way ofexample, a carrier wave, a transmission line, and any other suitablemedium for transmitting software and/or instructions that may beaccessed and read by a computer. The computer-readable medium may beresident in the processing system, external to the processing system, ordistributed across multiple entities including the processing system.The computer-readable medium may be embodied in a computer-programproduct. By way of example, a computer-program product may include acomputer-readable medium in packaging materials. Those skilled in theart will recognize how best to implement the described functionalitypresented throughout this disclosure depending on the particularapplication and the overall design constraints imposed on the overallsystem.

FIG. 20 is a conceptual diagram illustrating an example of a hardwareimplementation for an apparatus 2000 employing a processing system 2014.In this example, the processing system 2014 may be implemented with abus architecture, represented generally by the bus 2002. The bus 2002may include any number of interconnecting buses and bridges depending onthe specific application of the processing system 2014 and the overalldesign constraints. The bus 2002 links together various circuitsincluding one or more processors, represented generally by the processor2004, a memory 2005, and computer-readable media, represented generallyby the computer-readable medium 2006. The bus 2002 may also link variousother circuits such as timing sources, peripherals, voltage regulators,and power management circuits, which are well known in the art, andtherefore, will not be described any further. A bus interface 108provides an interface between the bus 2002 and a transceiver 2010. Thetransceiver 2010 provides a means for communicating with various otherapparatus over a transmission medium. Depending upon the nature of theapparatus, a user interface 2012 (e.g., keypad, display, speaker,microphone, joystick) may also be provided.

The processor 2004 is responsible for managing the bus 2002 and generalprocessing, including the execution of software stored on thecomputer-readable medium 2006. The software, when executed by theprocessor 2004, causes the processing system 2014 to perform the variousfunctions described infra for any particular apparatus. Thecomputer-readable medium 2006 may also be used for storing data that ismanipulated by the processor 104 when executing software.

FIG. 21 is a block diagram of an exemplary Node B 2110 in communicationwith an exemplary UE 2150, where the Node B 2110 may be the Node B 208in FIG. 2, and the UE 2150 may be the UE 210 in FIG. 2. In the downlinkcommunication, a controller or processor 2140 may receive data from adata source 2112. Channel estimates may be used by acontroller/processor 2140 to determine the coding, modulation,spreading, and/or scrambling schemes for the transmit processor 2120.These channel estimates may be derived from a reference signaltransmitted by the UE 2150 or from feedback from the UE 2150. Atransmitter 2132 may provide various signal conditioning functionsincluding amplifying, filtering, and modulating frames onto a carrierfor downlink transmission over a wireless medium through one or moreantennas 2134. The antennas 2134 may include one or more antennas, forexample, including beam steering bidirectional adaptive antenna arrays,MIMO arrays, or any other suitable transmission/reception technologies.

At the UE 2150, a receiver 2154 receives the downlink transmissionthrough one or more antennas 2152 and processes the transmission torecover the information modulated onto the carrier. The informationrecovered by the receiver 2154 is provided to a controller/processor2190. The processor 2190 descrambles and despreads the symbols, anddetermines the most likely signal constellation points transmitted bythe Node B 2110 based on the modulation scheme. These soft decisions maybe based on channel estimates computed by the processor 2190. The softdecisions are then decoded and deinterleaved to recover the data,control, and reference signals. The CRC codes are then checked todetermine whether the frames were successfully decoded. The data carriedby the successfully decoded frames will then be provided to a data sink2172, which represents applications running in the UE 2150 and/orvarious user interfaces (e.g., display). Control signals carried bysuccessfully decoded frames will be provided to a controller/processor2190. When frames are unsuccessfully decoded, the controller/processor2190 may also use an acknowledgement (ACK) and/or negativeacknowledgement (NACK) protocol to support retransmission requests forthose frames.

In the uplink, data from a data source 2178 and control signals from thecontroller/processor 2190 are provided. The data source 2178 mayrepresent applications running in the UE 2150 and various userinterfaces (e.g., keyboard). Similar to the functionality described inconnection with the downlink transmission by the Node B 2110, theprocessor 2190 provides various signal processing functions includingCRC codes, coding and interleaving to facilitate FEC, mapping to signalconstellations, spreading with OVSFs, and scrambling to produce a seriesof symbols. Channel estimates, derived by the processor 2190 from areference signal transmitted by the Node B 2110 or from feedbackcontained in a midamble transmitted by the Node B 2110, may be used toselect the appropriate coding, modulation, spreading, and/or scramblingschemes. The symbols produced by the processor 2190 will be utilized tocreate a frame structure. The processor 2190 creates this framestructure by multiplexing the symbols with additional information,resulting in a series of frames. The frames are then provided to atransmitter 2156, which provides various signal conditioning functionsincluding amplification, filtering, and modulating the frames onto acarrier for uplink transmission over the wireless medium through the oneor more antennas 2152.

The uplink transmission is processed at the Node B 2110 in a mannersimilar to that described in connection with the receiver function atthe UE 2150. A receiver 2135 receives the uplink transmission throughthe one or more antennas 2134 and processes the transmission to recoverthe information modulated onto the carrier. The information recovered bythe receiver 2135 is provided to the processor 2140, which parses eachframe. The processor 2140 performs the inverse of the processingperformed by the processor 2190 in the UE 2150. The data and controlsignals carried by the successfully decoded frames may then be providedto a data sink 2139. If some of the frames were unsuccessfully decodedby the receive processor, the controller/processor 2140 may also use anacknowledgement (ACK) and/or negative acknowledgement (NACK) protocol tosupport retransmission requests for those frames.

The controller/processors 2140 and 2190 may be used to direct theoperation at the Node B 2110 and the UE 2150, respectively. For example,the controller/processors 2140 and 2190 may provide various functionsincluding timing, peripheral interfaces, voltage regulation, powermanagement, and other control functions. The computer readable media ofmemories 2142 and 2192 may store data and software for the Node B 2110and the UE 2150, respectively.

Several aspects of a telecommunications system have been presented withreference to a W-CDMA system. As those skilled in the art will readilyappreciate, various aspects described throughout this disclosure may beextended to other telecommunication systems, network architectures andcommunication standards.

By way of example, various aspects may be extended to other UMTS systemssuch as TD-SCDMA and TD-CDMA. Various aspects may also be extended tosystems employing Long Term Evolution (LTE) (in FDD, TDD, or bothmodes), LTE-Advanced (LTE-A) (in FDD, TDD, or both modes), CDMA2000,Evolution-Data Optimized (EV-DO), Ultra Mobile Broadband (UMB), IEEE802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Ultra-Wideband (UWB),Bluetooth, and/or other suitable systems. The actual telecommunicationstandard, network architecture, and/or communication standard employedwill depend on the specific application and the overall designconstraints imposed on the system.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but are to be accorded the full scope consistentwith the language of the claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Unless specifically statedotherwise, the term “some” refers to one or more. A phrase referring to“at least one of” a list of items refers to any combination of thoseitems, including single members. As an example, “at least one of: a, b,or c” is intended to cover: a; b; c; a and b; a and c; b and c; and a, band c. All structural and functional equivalents to the elements of thevarious aspects described throughout this disclosure that are known orlater come to be known to those of ordinary skill in the art areexpressly incorporated herein by reference and are intended to beencompassed by the claims. Moreover, nothing disclosed herein isintended to be dedicated to the public regardless of whether suchdisclosure is explicitly recited in the claims. No claim element is tobe construed under the provisions of 35 U.S.C. §112, sixth paragraph,unless the element is expressly recited using the phrase “means for” or,in the case of a method claim, the element is recited using the phrase“step for.”

What is claimed is:
 1. A method of wireless communication, comprising:receiving from a base station, a primary scheduling grant comprising afirst traffic to pilot power ratio; transmitting a primary pilot channeland an enhanced primary data channel on a first virtual antenna of amultiple input multiple output (MIMO) uplink transmission, wherein aratio between the power of the enhanced primary data channel and thepower of the primary pilot channel corresponds to the first traffic topilot power ratio; determining a size of a packet transmitted on theenhanced primary data channel in accordance with the first traffic topilot power ratio by looking up a transport block size that correspondsto the first traffic to pilot power ratio; determining a reference powerlevel corresponding to a secondary pilot channel; determining a rank ofthe transmission; transmitting an enhanced secondary data channel on asecond virtual antenna of the MIMO uplink transmission based on thedetermined rank; and transmitting the secondary pilot channel on thesecond virtual antenna at a boosted power level relative to thereference power level, wherein a difference between the reference powerlevel and the boosted power level is determined in accordance with thesize of a packet transmitted on the enhanced primary data channel,wherein a ratio between the power of the enhanced secondary data channeland the power of the secondary pilot channel corresponds to the samefirst traffic to pilot power ratio, and wherein the first virtualantenna and the second virtual antenna utilize the same carrierfrequency.
 2. The method of claim 1, wherein the reference power levelis the same power level as a power level of the primary pilot channel.3. The method of claim 1, wherein the reference power level is offsetrelative to a power level of the primary pilot channel.
 4. The method ofclaim 1, wherein the transmitting of the enhanced secondary data channelcomprises transmitting the enhanced secondary data channel during afirst transmission time interval, the method further comprising: ceasingthe transmitting of the enhanced secondary data channel during a secondtransmission time interval; and transmitting the secondary pilot channelon the second virtual antenna at a second power level during the secondtransmission time interval, wherein the second power level is offset bya predetermined amount relative to the primary pilot channel.
 5. Themethod of claim 1, wherein the primary pilot channel comprises adedicated physical control channel (DPCCH); and wherein the secondarypilot channel comprises a secondary DPCCH.
 6. An apparatus configuredfor wireless communication, the apparatus comprising: means forreceiving from a base station, a primary scheduling grant comprising afirst traffic to pilot power ratio; means for transmitting a primarypilot channel and an enhanced primary data channel on a first virtualantenna of a multiple input multiple output (MIMO) uplink transmission,wherein a ratio between the power of the enhanced primary data channeland the power of the primary pilot channel corresponds to the firsttraffic to pilot power ratio; means for determining a size of a packettransmitted on the enhanced primary data channel in accordance with thefirst traffic to pilot power ratio by looking up a transport block sizethat corresponds to the first traffic to pilot power ratio; means fordetermining a reference power level corresponding to a secondary pilotchannel; means for determining a rank of the transmission; means fortransmitting an enhanced secondary data channel on a second virtualantenna of the MIMO uplink transmission based on the determined rank;and means for transmitting the secondary pilot channel on the secondvirtual antenna at a boosted power level relative to the reference powerlevel, wherein a difference between the reference power level and theboosted power level is determined in accordance with the size of apacket transmitted on the enhanced primary data channel, wherein a ratiobetween the power of the enhanced secondary data channel and the powerof the secondary pilot channel corresponds to the same first traffic topilot power ratio, and wherein the first virtual antenna and the secondvirtual antenna utilize the same carrier frequency.
 7. The apparatus ofclaim 6, wherein the reference power level is the same power level as apower level of the primary pilot channel.
 8. The apparatus of claim 6,wherein the reference power level is offset relative to a power level ofthe primary pilot channel.
 9. The apparatus of claim 6, wherein themeans for transmitting the enhanced secondary data channel comprisesmeans for transmitting the enhanced secondary data channel during afirst transmission time interval, the apparatus further comprising:means for ceasing the transmitting of the enhanced secondary datachannel during a second transmission time interval; and means fortransmitting the secondary pilot channel on the second virtual antennaat a second power level during the second transmission time interval,wherein the second power level is offset by a predetermined amountrelative to the primary pilot channel.
 10. The apparatus of claim 6,wherein the primary pilot channel comprises a dedicated physical controlchannel (DPCCH); and wherein the secondary pilot channel comprises asecondary DPCCH.
 11. A computer program product, comprising: anon-transitory computer-readable medium comprising instructions forcausing a computer to: receive from a base station, a primary schedulinggrant comprising a first traffic to pilot power ratio; transmit aprimary pilot channel and an enhanced primary data channel on a firstvirtual antenna of a multiple input multiple output (MIMO) uplinktransmission, wherein a ratio between the power of the enhanced primarydata channel and the power of the primary pilot channel corresponds tothe first traffic to pilot power ratio; determine a size of a packettransmitted on the enhanced primary data channel in accordance with thefirst traffic to pilot power ratio by looking up a transport block sizethat corresponds to the first traffic to pilot power ratio; determine areference power level corresponding to a secondary pilot channel;determine a rank of the transmission; transmit an enhanced secondarydata channel on a second virtual antenna of the MIMO uplink transmissionbased on the determined rank; and transmit the secondary pilot channelon the second virtual antenna at a boosted power level relative to thereference power level, wherein a difference between the reference powerlevel and the boosted power level is determined in accordance with thesize of a packet transmitted on the enhanced primary data channel,wherein a ratio between the power of the enhanced secondary data channeland the power of the secondary pilot channel corresponds to the samefirst traffic to pilot power ratio, and wherein the first virtualantenna and the second virtual antenna utilize the same carrierfrequency.
 12. The computer program product of claim 11, wherein thereference power level is the same power level as a power level of theprimary pilot channel.
 13. The computer program product of claim 11,wherein the reference power level is offset relative to a power level ofthe primary pilot channel.
 14. The computer program product of claim 11,wherein the transmitting of the enhanced secondary data channelcomprises transmitting the enhanced secondary data channel during afirst transmission time interval, and wherein the non-transitorycomputer-readable medium further comprises instructions for causing acomputer to: cease the transmitting of the enhanced secondary datachannel during a second transmission time interval; and transmit thesecondary pilot channel on the second virtual antenna at a second powerlevel during the second transmission time interval, wherein the secondpower level is offset by a predetermined amount relative to the primarypilot channel.
 15. The computer program product of claim 11, wherein theprimary pilot channel comprises a dedicated physical control channel(DPCCH); and wherein the secondary pilot channel comprises a secondaryDPCCH.
 16. An apparatus for wireless communication, comprising: atransmitter for transmitting a primary virtual antenna and a secondaryvirtual antenna of a multiple input multiple output (MIMO) uplinktransmission; at least one processor for controlling the transmitter;and a memory coupled to the at least one processor, wherein the at leastone processor is configured to: receive from a base station, a primaryscheduling grant comprising a first traffic to pilot power ratio;transmit a primary pilot channel and an enhanced primary data channel onthe primary virtual antenna, wherein a ratio between the power of theenhanced primary data channel and the power of the primary pilot channelcorresponds to the first traffic to pilot power ratio; determine a sizeof a packet transmitted on the enhanced primary data channel inaccordance with the first traffic to pilot power ratio by looking up atransport block size that corresponds to the first traffic to pilotpower ratio; determine a reference power level corresponding to asecondary pilot channel; determine a rank of the transmission; transmitan enhanced secondary data channel on the secondary virtual antennabased on the determined rank; and transmit the secondary pilot channelon the secondary virtual antenna at a boosted power level relative tothe reference power level, wherein a difference between the referencepower level and the boosted power level is determined in accordance withthe size of a packet transmitted on the enhanced primary data channel,wherein a ratio between the power of the enhanced secondary data channeland the power of the secondary pilot channel corresponds to the samefirst traffic to pilot power ratio, and wherein the primary virtualantenna and the secondary virtual antenna utilize the same carrierfrequency.
 17. The apparatus of claim 16, wherein the reference powerlevel is the same power level as a power level of the primary pilotchannel.
 18. The apparatus of claim 16, wherein the reference powerlevel is offset relative to a power level of the primary pilot channel.19. The apparatus of claim 16, wherein the transmitting of the enhancedsecondary data channel comprises transmitting the enhanced secondarydata channel during a first transmission time interval, and wherein theat least one processor is further configured to: cease the transmittingof the enhanced secondary data channel during a second transmission timeinterval; and transmit the secondary pilot channel on the secondaryvirtual antenna at a second power level during the second transmissiontime interval, wherein the second power level is offset by apredetermined amount relative to the primary pilot channel.
 20. Theapparatus of claim 16, wherein the primary pilot channel comprises adedicated physical control channel (DPCCH); and wherein the secondarypilot channel comprises a secondary DPCCH.